Hi Paul,
The service manual for this power supply is available from various online resources for free such as here :-
https://elektrotanya.com/kenwood_ps-50_sch.pdf/download.html
plus an online visible one here :-
https://www.manualslib.com/manual/557564/Kenwood-Ps-50.html?page=4#manual
I did find a picture on the following link although it's not all that clear :-
http://2.bp.blogspot.com/_-INr63nsUkM/TAnkLMyWOgI/AAAAAAAAAaU/rgBEqw5WyzU/s1600/kenwood+ps-50_insideview.jpg
Hopefully between that lot you should be able to get sorted.
Have fun.
All the best,
Victor