A agree with the post about not using solid state rectifiers. I use a
pair of 3B28s instead of "Old Sparkey" (the 866s). I do, however, use a
pair of 1N4007's in the neg bias rectifier circuit. Regarding the paper
caps, I change them all out, en masse. While you have your unit out of
the case, please check the two meter shunts (plate and mod current).
These nichrome shunts are very prone to be off by quite a bit. You can
rebuild the shunt (there's usually enough length, either way. I've
taken to using fixed resistors instead of the wire jobs and it seems to
work OK. Finally, consider adding an additional fuse to individually
protect the 2 power transformers.

PatW wrote:

Just got a Johnson Valiant and will be restoring it. It appears to be in
fair condition and has the user manual. But, is missing the schematic.
Any ideas on where to get a schematic for this ?