had one intermittently go on earthquake from day one of the mod, could not find the problem, so many hours on that call, anyway ended up moving the earthquake input from the car serial link to the group or hall link, can't remember which now, any way removed car link from eq board, and added it to other link and readdressed it. no more earthquake problems. however it started cancelling calls intermittently if you gave it a lobby and a bottom floor car call, it would just cancel the calls and stop at next floor. problem was in the car serial link, can't remember now, but think it was a bad rsl board or improperly terminated rsl board in the car top emergency circuit. we could watch the HZ of the car serial link drop from i believe 1220 hz to a much lower number, this would cause the problem. keeping an eye on the frequency of the car link eventually led us to the cartop after much more work. the only problem with moving the eq circuit to the other link, was there was no input for eq reset on that link, so if it did go on eq, you would have to put the car link back on the board, readdress the input, and then reset.