I bought a used/dead one to add a second unit to the house for my wife (originally just for the faceplate, since mine got pretty scratched up in a move, but decided to fix it), and first it had a down multiolex stage (sorted cap) and then would not release muting (yet another shorted cap), so while I specifically debugged the two problems down to specifuc parts, I also did a pretty complete recall of electrolytics.
Other than better parts, no upgrades - I never found it to be lacking to begin with. (Oh, and just a TX-11, not an a or b).
No alignment at this time - seems stable, and not changing anything in the RF section (nomelectrolytics there anyhow) so as to not effect tuning. Not sure my FM stereo generator outputs what they are looking for (and need to make sure it is working as well - not been used in quite a few years).