[Drake] R4A receiver

[Sandy, W5TVW]

Is there available the layouts with parts callouts for the "component" boards in the
R4A receiver?  When one has burned up resistors, finding out where they are in the
diagram
can be VERY difficult to trace out!  Drake didn't see fit to originally do this in
their books.  (Unfortunately).
Is there any "caveats" on removing and replacing the PTO assembly?  My R4A is
jumping around randomly in frequency.  I tried the "yoke grounding" mod with no
results.  Probably a part on the PTO PC board.
73,
Sandy W5TVW