OEM Electrolytics drifting high???

[DavGoodlin]

While working on the preamp section of a 1966 Packard Bell Console RPC-66, covered by SAMS 902, I have found some common Nichicon caps, the last few I need to replace.

The problem: C315 and C316 are labeled as 25 mf @ 3 volt and measured 124ufd (!) on a Fluke DMM.

C317, 318 and 319 labeled 50 uf @ 6V measured 221 ufd. I will double check on the EICO 950 but expect the same and checking for breakdown voltage, which the 950 does up to 500v, on a 6 volt cap is just impractical.

Note that my intended new replacement caps, measure 26 and 48 uf respectively. I'm used to original parts measuring lower, but not this.

Do these caps fail by increasing in capacitance? I expected a decrease in capacitance attendant with an increase of ESR.