Europa-List: My Apollo/Garmin SL70 transponder needs repair

[Karl Heindl <kheindl@msn.com>]

This is the second time in 3 years that my transponder is failing. Does any
one know a reliable repair shop=2C anywhere in N. America or Europe where I
 might pay a lot less than the usual $ 450 quoted me by Apollo ? Or is a us
ed one available anywhere=2C where it was replaced by a Mode S ?
My unit comes up with TEST FAIL=2C and it seems to refer to the transmit an
d receive. It happened a couple of times in flight=2C but then came back to
 normal.  Now it is permanent.Any ideas out there ? Would appreciate any hi
nts.
Karl