796D fault & solution
If memory serves, this is my first post. Hopefully, the following notes might help a user........
I've had my 796D in desktop use for about 5 years now, and just took it on a ten-day mobile trip. Toward the end of the trip, a keypad problem developed:
First the "hold" button became intermittent, becoming inoperative after a while. Also found the "RSM, Limit, and Trunk" buttons inoperative...note they are all the same vertical column in the keypad---they share a common signal in the keypad encoder data formatting. All other buttons work, although without the 4 dead buttons, it's pretty useless.
The solution: (touch the metal frame of the scanner to eliminate any static charge between you and the scanner before grabbing circuitry)
Remove the bottom panel, taking care with the short and light duty speaker wires--you can fold the cover back or unplug the speaker from the main board, and remove the cover entirely. You'll see two flat flex pcb-style strips between the main board and the control panel...these are the multi-conductor "wires" carrying the keypad info. In my case, one of the connections was loose --- the ribbons plug into small female connectors on the main board and control panel --- I was able to wiggle these without unplugging them entirely.
A quick test showed all problems to be resolved.
I have always been pleased with the 796D and related product line for overall robust construction and reliable circuitry---I was disappointed, although not surprised, to find the relatively flimsy connections, which have no restraints or latches whatsoever.
best to all