HP DesignJet 755cm Carriage problems

[Dave Carwile]

After replacing carriage belt , carriage moves smoothly , prints alignment pattern and then briefly flashes "Ready" and immediately goes back into alignment again. Ends up w/ error codes . Fails Drop Detect calibration. Errror codes of 030003 001601C7 and 070000 EEEEEEE . Also sometimes get " Check Cartridge Path".
Longtime copier/wide format tech. First time working on Inkjet plotter. Greatly appreciate any and all advice. Dave

[Dave Carwile]

One for the books. Spent 1 hr replacing belt/cleaning, 3 hrs troubleshooting and trying to pass calibrations. Decided we needed to pull machine to office for repair. Carried plotter down 2 flights of stairs, loaded in truck and carried over 40 miles of bumpy roads. Take it into office and it immediately comes to ready. Passes every test, calibrates and prints beautifully. Go figure.

[fixthecopier]

Hard to say, but I used to have that happen with fax machines, where they fixed themselves on the way back to the shop. I just brought back one of that model today, I hope it will fix itself also.