Anyone experience with bad contacts on universal PLCC ZIF socket?

[Kjelt]

So since a year I have this expensive 2^nd hand device programmer from BP Microsystems and yesterday I tried to read and program some eprom in a PLCC package using an
ARIES 20-84 pin PLCC ZIF socket.

No matter what I tried (clean the socket- and device- contacts with IPA, pressing the chip down manually) I could not get the device to read properly.
It started out with 4 bad contacts, now it still has one to two bad contacts (after cleaning and manually pressing the ic).
Does anyone have a solution for this problem or a similar bad experience with these universal ZIF sockets, I mean they cost $300 incl faceplates, something that expensive better work?

http://www.arieselec.com/products/data/10010-universal-plcc-zif-test-socket.pdf
http://www.digikey.com/product-detail/en/aries-electronics/84-537-21/A331-ND/4822