I recently purchased (on eBay) a Porsche 9201 Timing Belt tool to check my timing belt. It came with the calibration bar and when I check it, it reads approximately 3.7 which is in the lower limits of acceptable (4.0 +/- 0.3).

The factory manual tells you who to adjust to calibration with a small screw driver. However, I do not seem to find a slotted screw like I expected. I used an otoscope (ear exam tool) to look into the adjustment hole, and I do not see a slotted screw!

If anyone has experienced using the 9201 gauge and have they ever attempted to readjust the calibration?

Also, has anyone ever sent their gauge back to the supplier to be re-calibrated?

Thanks in advance.

Dale