92 Isuzo PU. Driver door won't open. Window goes down only half way. I can hear a "clunk" when it reaches the half way point. Can't take the pannel off because I can't open the door. It seems like the outside door handle no longer works. I have verifed that the inside one is attached to the relay bar, but it won't trip the latch. The push button lock is down and won't release. Any ideas?