as their parts are either new or remanufactured, Chances are you Digitalconvergence unit is defective instead, or quite possibly the the VM board more...
JVC AV-56WP30 56 in. Rear Projection... - Troubleshooting
If they tested the convergence board and thats ok, the only other Items it could be are the Digitalconvergence unit or the Velocity comando units that control the convergencemore...
JVC AV-56WP30 56 in. Rear Projection... - Troubleshooting