[ScottSirens]

Yeah I used to use this method as well, but spit on the cart contacts will build up a rust on the contacts that can ruin them.
If you look inside the arm you will probably see a residue on the contacts try and take a bobby pin or something sharp and small enough to fit inside the arm and scrape clean the contacts. Once you have started using spit,water, etc to conduct electricity thru the arms you might be screwed and stuck using that method until you replace the arms or contacts.

It is also possible to take the tone arm off and pull the contacts out farther so they make contact with the needle end but I am not experienced in doing this, Frankie Vega is the one who told me about this so maybe he will see this thread or you can track him down for more info

hope this helps
peace