Questions on capacitors

[giosif]

Hi,

I have two questions with regards to some electrolytic capacitors I found while troubleshooting a power supply (please see attached photos):
1. A 1000uF cap whose "skirt" got lifted.
    I am guessing this might be due to proximity to something getting hot.
    But the interesting part is both Cs and Rs/ESR are very close to those of a brand new cap with the same specs.
    At the same time, if I look at the bottom of the cap with the light shining at an angle, there seems to be a substance present there (could be electrolyte, but could just as well be flux from when it was soldered initially).
    I am replacing this cap anyway, but I was wondering if you would consider this cap as good (based on measurements) or bad (based on exterior details).

2. A 220uF cap (light blue one) which I would like to replace.
    However, I'm slightly puzzled by the replacement cap I found in my stash, as the physical dimensions are quite different.
    Are these two caps really equivalent, or am I missing some parameter here (other than capacity, working voltage and ESR, which are the same between the two)?

Thanks!

[Labrat101]

replace it . that discolouring looks like that it has been tracking over
the base . 
If the cap is getting hot maybe due to over voltage or high ripple due
to Another Fault . As its on a power supply check the bridge rectifier it
could be failing . There are many reason a cap fails and the ESR can
show good but if leaky it will fail as the cap is loaded .
 Cap's in short can show good have a fairly close Uf rating but it will
depend on the Manufacturing quality .
If you have removed a cap from a board and its a few years old replace it.
Depending on the age of these I would also check for a reason and other components that are loading the cap.
The Blue cap as you say looks like a high ripple cap
  YXF for secondary filtration in power circuit, aiming at small size, high ripple-resistance, low impedance .
You should also check the big 400v caps these are more likely to be your problem .

 
RNS

[giosif]

Thank you for the good advice!
I will replace the bigger cap and look for other faulty components.
I will also check to find a more suitable replacement for the blue cap.
(The 400V cap has already been replaced, BTW).

[Doctorandus_P]

The blue cap is probably just fine.

The physical size of electrolytic caps has been shrinking ever since they first started manurefacturing them a long time ago. The big one is probably just 10+ years older then the black replacement.

If you can find the exact datasheet of the series of both capacitors, then you can do a comparison of their spec's.