All you need is prints and five boxes of 110 ice cubes hahah

and a relay tester

MRs equipment is not that bad.
Usually look for burnt spots on the relays.
Most of the problems are the relays in the back for the doors.
Hopefully it has the electronic stepper board instead of the original stepper switch.
Check the limit switches in the hoistway to make sure they are not those that turn to goo.
Occasionally you will have a sensor on the car top go bad.
And the switches on the door operator.That is if you have the 7300 door operator.

Finally fixed all the shorts and grounds and got the car running. It ran for over a day and then trapped someone. Reportedly it was "running the shaft". We've replaced the stepper and cartop selector board. Not sure why it keeps going back to the original problem which was running up and down and not stepping.. maybe a simple contact failure.

I had a similiar problem last year..when I had reclaimed this unit on maintenance..found when elevator would run fine on multi-floor runs..top to bottom..no problems..but when going on one floor runs.accelleration was so fast 2E circuit was not allowing the proper stopping sequence..which would cause the stepper to go out of step.when car stopped it would not open doors cause it was lost and trap people..the fix was timer to delay the pick of the 2e circuit..this problem never came back and car has been running flawless to date..hope this helps..

Check the making contacts in the direction limits. Or is the car not stepping at all? Or too many times? Does tco or bco relay pick during runs?