A:
Hello - this is Nancy at GE and we are sorry to hear that your microwave stopped working just before Thanksgiving. I am very happy to help you.
Yes, the PEB7226SFSS is a great replacement for the JEB1860SMSS. The new trim kit that you will need for a 30" cabinet is the JX7230SFSS. The new trim kit is necessary because the screw holes, ventilation and cosmetics have changed. The trim kits and microwaves have to be approved together for use. The good news is that both your old and the new trim kit require the same cabinet cut-out dimensions.
I hope this helps! Thank you for contacting GE!