I agree with Joe. If you are seeing the case of the caps bulging or bubbling they should go.
The caps for the heater supply are axial leads so easy replacements are still made. They will be physically smaller the the '60s technology caps. Here is a link to the manual: https://www.hifiengine.com/manual_libra ... s-3x.shtml
Sadly the parts list does not give the voltage rating for the caps. As Joe said it should be printed on the cap but 50 Volts should be overkill and will still likely be physically smaller than the OEM parts.
I'm hoping that when you did the selenium to silicon rectifier conversion you checked the heater voltage and added a resistor to make it reasonable.
The lamp is fed from AC upstream of the rectifier diodes and capacitors so the caps affecting the lamp is unlikely, however if the caps have significant leakage which varies I could conceive of how they could do that, however first check the soldering to the socket and the cleanliness of the contacts in the socket. Also you can monitor the AC voltage across the socket as the lamp flickers. If it is steady or rises as the lamp dims, replace the socket.
The Twist lock can electrolytic caps for the B+ supply are of the same age as the ones in the heater supply so they may be approaching their end of life as well. Exact replacements for those may be available but they will be speciality items and therefore spendy. I would favor newly made replicas for those as opposed to NOS as the seals can fail over the years.
Some folks gut the old caps and put modern caps inside the case to preserve the look. I have been known to do that.
MRag wrote:Hello Again All,
So I finally did the replacement of the selenium rectifier as per CurcioAudio - went fine. I'll even post some pictures eventually. But during the replacement I did notice a bubble on the positive seal on both of the electrolytic capacitors. Do you suggest I replace those as well? Maybe those are the weak link causing my power indicator lamp to still flicker? For all I know those are the originals.
IF I replace these electrolytic caps, I see their value is 2,000 MFD or uFD, but the main question is what voltage value should these be? I cannot find anywhere in the schematic or understand what is correct. Any thoughts are once again much appreciated.