Considering the slow discharge of the cap, it is probably good and without an RCL meter with loss capabilities, it would be tough to condemn it. In most cases I've seen, the larger filter caps are not at fault but rather caps in the range of 4.7-100uFd that are used in the feedback path. The voltage ratings are seldom over 50VDC. These are exposed to high frequencies and if a standard electrolytic is used (they are cheaper) they will eventually fail due to the decay of the chemicals in them. You might check for a radio amateur club in your area since one of the members might well have an RCL bridge/meter with DF capabilities. If you find one with more than one frequency range, a bad cap will show a major decrease in capacitance and increased losses at the higher frequency. Good luck-
Answers & Comments
Considering the slow discharge of the cap, it is probably good and without an RCL meter with loss capabilities, it would be tough to condemn it.
In most cases I've seen, the larger filter caps are not at fault but rather caps in the range of 4.7-100uFd that are used in the feedback path. The voltage ratings are seldom over 50VDC. These are exposed to high frequencies and if a standard electrolytic is used (they are cheaper) they will eventually fail due to the decay of the chemicals in them.
You might check for a radio amateur club in your area since one of the members might well have an RCL bridge/meter with DF capabilities. If you find one with more than one frequency range, a bad cap will show a major decrease in capacitance and increased losses at the higher frequency.
Good luck-