Pentax Repair Service (%^&$*)

Woah - hang on a sec. Clearly the lens was working when you got it back so QC isn't an issue here. Pentax repaired your lens and tested it. Worked fine. Sent it to you. You tried it. Worked fine.

Then you removed it from your camera, replaced it later on, and it wasn't working.

This could indicate a few things may be responsible.

1. The AF circuit is getting fried by your camera (faulty camera).

2. The AF circuit is getting fried when you remove the lens or replace the lens on your camera (is the camera turned off when you remove or replace the lens?)

3. The AF circuits aren't handling the specified voltages.

4. You're using a non-standard battery which may be faulty

I'd recommend you ensure your camera isn't frying the lens since it wuld be a shame to have to send the lens back a third time.

--
http://www.pentaxphotogallery.com/jamesverhoeven
http://community.webshots.com/user/jimbob_productions