Hi there, yes there's a chance it is ur leads that are the problem.
Have you tried other needles/headshells in the problem deck?

A bad headshell connection can also possibly be to blame.
Firstly i would suggest that u unscrew the headshell and have a close look into the end of the tonarm.
The 4 little contacts in there are supposed to be sprung a little, check that these aren't "stuck". Sometimes they get stuck all the way pushed in (usually a result of dirt, age, or most likely - headshell has been overtightened).
also check they are clean, if not use a cotten bud to carfully clean them.

Not the problem? try checking:
- Check the headshell contacts are clean, i find buffing the headshell contacts by carefully and vigorusly rubbing the base of the headshell on my trouser leg (or a dry duster streched over my leg) an effective way to get them nice n shiny :-)
- Check the 4 little wires connecting the catridge to the headshell arein good nik + connected properly (google search if u need to check which way they go)
-if none of these help then I would suggest checking with a continuity tester/multi-meter from each of the tonearm springy contacts to the phono plugs. Each spring contact should bell through to one of the phono connectors contacts, check all 4 wires bell through, failing this put ur meter on ohms and repeat this step checking the resistance when belling them out, find 1 with a high resistance then thats your problem.
Hope this helped
:-) Dj E-mission