http://forums.rennlist.com/.... look up "window problems" and you will see my post with my rennlist name "clb0099". It could be the regulator,motor,or the fact of wires getting corroded... you can eve look up all my posts . I had both windows replaced new regulators and new wiring harness. I hope this helps
well here is the short answer... 320 for labor per side for replacing wires. The wiring was another 165.00 since i did not going with the complete wiring harness update but just the wires and connections. So it was 640 labor for the doors and 230 for the parts. The regulator for both sides i bought from ebay which were 160 from a crashed 2002 boxster and i bought new motors also from ebay which cost 120. The regulator you can change out yourself very easily maybe 2 hrs of work . The wires i would not even attempt since there is like 43 wires. There is a write up on replacing the regulator on rennlist i believe . I hope this helps