I have an older side by side Maytag refrigerator Model RSD2200CAL DM12A and had ice buildup in freezer. I used hair dryer to clear the ice and fridge is working again. I would like to manually start the defrost cycle with the defrost timer (Believe it to be Model 68233-3) but cannot find it. Does anyone know where exactly the timer is tucked away. Any help would be appreciated!!

Eureka..never would have thought of looking there. Had to peel back a bit of insulating cardboard to have access to manual screw. Advanced it until it clicked and compressor shut off, unfortunately no defrosting happening. Removed plate holding lower heating tube and found it to be what appears to be the culprit. It was all black and am assuming burnt out. Off to website to buy replacement heater part and hopefully get defrost cycle working again. Note the compressor did kick back on after approx 20 minutes. Thanks so much for your assistance.