Symptoms: on screen display intermittent and sometimes not readable, oven would lock up every few days and not be usable until breaker was reset
First I just ordered the Digitron (Part #WB27X10856) and that helped for a few weeks but then the oven/mw started locking up and the only way to get it to work was reset the breaker.
Ordered both of these Pwb(pcb)Asm Sub (Part #WB27X10858) and (Part #WB27X10861) and that fixed the problem entirely.
Installation was relatively easy - phillips screwdriver was all I needed. Took about 20-25 minutes. Most tedious part was threading the wiring harness back in which was still fairly quick. Take your time and anyone can get the installation done.