Hi!
The service manuals are out there, just google them. And then apply the three golden rules of electrolytic capacitors of that time, where this unit was built:
1) Exchange all electrolytic caps.
2) Exchange all electrolytic caps, that just looked fine.
3) Exchange all caps that you forgot.
In the service manuals there are lists of all parts. I have a SL4031 and I used google tabs to ma a list of all parts. As almost all of the capacitor manufacturers listed in the service manual have vanished form the marked (probably as all their caps leaked), Schlumberger advised their service personell to replace all caps by Panasonic branded ones of the same types. Please watch out for discoloration of parts and PCBs around these Caps, especially the SMD ones. You have to clean these areas very very thoroughly. On the RF boards, check the vias.
I do not see any problems in replacing them with the same values, but remember that, the higher the voltage rating is, the higher the chance, that the cap is positive in tolerance. So look for same µF value but higher voltage. But (yes, there is always a but) be careful of the sizes. It makes no difference in putting a 2mm pin distance into a 2.5mm hole layout. But trying to solder an 6.8mm SMD cap onto 6.2mm pads does make big problems...
Other than that: First start with the power supply. With a chance of slightly over 154% the -15V are pretty unstable. Use good quality caps for the replacement. I used 732-9534-1-ND and 732-9612-1-ND from digikey and I also replaced all other caps in the PSU with Würth.
Advise for the plug-in boards: Handle with care and using ESD strip is a must, must, must! Some very important parts of this unit are not available anymore. For example, on the 433,92MHz oscillator is a BFG92A, that I cannot find anywhere. BFG92A/X are available from a broker and are also relatively cheap, but the pinning is not the same. The A has the two Emitters on one side, the A/X has them across each other.
If you have more questions, just ask
73!