Maytag WU490 Dishwasher - temporarily stops mid cycle

Maytag Dishwasher WU490 (had it since 1989) - runs fine except sometimes will not drain water at end of cycle but can see timer still running. Shut it off, wait 20 minutes or so and back to running okay when turned back on. While stopped, moved timer to other cycles and nothing runs - no washing, no draining, no filling but timer runs and all okay when it decides to run with water again. Water level switch working. Does run complete cycle when heated wash not used so maybe thermostat issue but can’t find it to bypass it - anybody know where it is - maybe behind the plate that the heater electric connects to? Any other ideas? Just want to avoid getting a new dishwasher that runs for hours and they are all work the same. This one only take about 45 minutes. I will keep running it until it completely craps out.