George, what you do is affected by what you want to end up with.
Where you just want to make it work again, be safe and look nice but not go overboard, the level that I took that K15 to would be about right. That was not a true 100% restoration as I used materials and techniques that were different to that originally used.

I would dismantle the entire set back to "kit level" and refurbish each part.
To clean off that "!#$%" lot of paint I would use a solvent that will soften the paint to allow it to be brushed off. The solvent must not affect any part to the point of damage while loosening the paint. I would not use steel wool or sandpaper on any part. Anything you rub or brush a surface with will leave scratches! Nothing looks worse than a metal part with swirls and scratches, IE alloy coil cans polished bright or sandpapered chassis. I have a bottle of everything on standby, turps, metho, kero, windex, thinners from Bunnings. There will be a solvent there that will attack the base of most paints. Alternatively if the parent material of a thing can stand it, a more chemical means may be appropriate using an acid or alkali to loosen the bond layer of the paint. Hence the beloved "mollasses" baths or 20 liters drums of fruits dissolved into an unholy concoction (pigs swill). You can put a painted object like suspension parts or heads or blocks in there and they come out clean as a whistle!

With that K15 I used whatever gentle solvent would not attack the metal, plastic, bakelite, ceramic a part was made of and used toothbrushes or nail brushes to scrub out the grease paint gunk and leave a matt original surface. The chassis needed the go in a chemical bath to remove gunk, rust and leave a clean metal. THEN I should have passivated and plated the metal. Not wanting to open up a laboratory I settled on drying the surface (which will then rust like a shot) and painting the surface with thin etching undercoat and then a thin top coat of alluminium paint that approximated the original passivated plated finish.
Things like valve sockets that are moulded octals can be soaked in thinners or meths safely and toothbrushed clean. The transformer needs carefull handling to clean off the excess paint (careful wire brush on the laminations!) and careful use of turps on bakelite strips. THEN possible drying in an oven (just push the missus out of the way) or use the old electric oven NOT GAS! A transformer can be wholly dipped in polypaint like the stuff they paint floors and cabinets (Wattyl clear coat) but TURPS BASED not WATER BASED. You could then dip the whole thing in black paint if you have cans big enough to take the size, if not rattle can paint. In summer just leaving parts out in the sun can dry them out.
You have to look at each part and work out what wont hurt it but take the "patina" off and look natural again. then you have to make each part functional like the dial and pots. Replacing components: here is where I just solder in NEW parts blessing how much smaller modern parts are. You can hollow out old parts to fit new parts in, but jeez I've got other things to do to better to pass the time! Here is also where I depart from the concept of restoration the wiring. While I got away with using the original loom in the K15 other radios I have used modern plastic wires of all colours to look pretty and tie wrapped them. I think nice squared up tidy wiring and component placing is far more important that originality.
O dear I have rambled a bit there and wandered about...hope some of that helps!
Ask me anything you are concerned with.
Fred.

In relation to 5Y3 there is actually only one position which it can be run sideways #80 is the same animal but with a UX 4 base.

Provenance can be found on the tube data sheets. As that is basically like a flat filament inside an air conditioner duct , that filament especially when it gets a bit of age on it, can sag. When placed in the wrong orientation the filament can (and has) hit the plate & created a fireworks display.

Thanks Ian and Fred, you are right, it does depend on what you want to end up with. This is not a radio I would try to overly worry about originality but It would be good one for me to get the confidence to fully strip it clean it and experiment with solvents.
So when I get one to do that is to one that is more important to me and rare and would benefit with original restoration after a complete strip down then may I can use this experience to not mess it up.

I am looking forward to this one.

I still need to get confirmation of the correct schematic for this chassis or I might need to draw up my own from what I have another go experience.



Marc I will certainly be more carefull of the position of those valves when taking voltage measurement etc, I often put s chassis on it's side to get access, would fully upside down be ok?

Thanks again

Paint: Methylene Chloride attacks most of those early paints. Full face shield or similar as it is not good for eyes & skin. Do not that it may be lead based. Do not handle food without washing. Food & drink is banned from this workshop.

You will have to remove the IF cans and there insides if the can needs work. As has been noted, make damn sure you mark the terminals and what they connect to. Different coloured paint dabs on them is useful.

Soda Ash (Sodium Carbonate) is great for removing Mouse doo with dishwashing liquid added to the mix. However, it will attack Bakelite to some extent so get the crap off & wash it off quick: It will de-lustre a cabinet.

You may be able to wire brush most paint & a lot of the rust from the chassis surface, but what is left will still need to be killed. If it has eaten into the surface some of those Pottassium Permanganate brews may prove infective.

I have run 5Y3 & many other valves upside down, HMV had a habit of putting a cage on their units, so you turn the chassis upside down without bending anything …. Pity many others did not follow suite. The Russian 5Y3 is built different & has a single filament like a pencil, cathode sleeve & the plates look like two tank stands on up one down. Considerably more robust.

I (as written frequently) draw the layout of everything, orientating valve sockets etc. as they are and numbering the pins. same deal for coils & If transformers. I use an AutoCAD which has most of the symbols etc. Once you have the layout: You translate it into a schematic.

All positively time consuming.