[Test-Equipment] Sprague TO-6A question

[Ken Kaplan]

I was trying to test some old 600v paper caps (Black Beauties, etc.) 
tonight and didn't see what I expected. I got nearly infinite insulation 
resistance. My really old caps (some from the 1940's) tested as good as 
some brand new caps I just bought. Hmm - maybe the TO-6 is faulty? I 
placed a 33 megohm resistor in parallel with a cap and it had no effect. 
I still had nearly infinite resistance. Then I tried it with a 1 meg 
resistor - same thing. I was using the L range and following the manual. 
The voltage seems to settle around 420v when the pointer is over the 
"Set" point. The TO-6 works great with electrolytics. This is the first 
time I've tried electrostatics. Any one here use a TO-6?

Thanks,
Ken