[Driver Ed]

After a long holiday-related pause, I'm back under my car. I've replaced the IMS bearing, and the RMS seal and have replaced the tensioners and refilled the engine with oil. I then attempted to check to make sure that the cam chains hadn't skipped a tooth, but I find I can't rotate the engine all the way through to 360 degrees. The first half rotation was fine (spark plugs are still in place, so there was a point at which arm-power was providing compression) but I got it to about 340 degrees rotation and it just won't budge.

Eyeballing the marks I made on the camshafts before removing the IMS bearing, they both (exhaust cams on 1-3 and 4-6) look about the same distance away (so I'm guessing neither has skipped a tooth) but I would really like to definitively check and can't figure out what could be stopping the engine from further rotation.

My car is a 2000 Porsche 996 with a 5-chain engine.

Any advice? I would really like to get this job done!