This oven has been great. Installed in 1997 it has performed very well.

Recently it has started to not come to the set temperature or goes above the set temperature 5 to 10 degrees.

More often than not, when the oven is started and the temp is set it begins the warm up cycle and most always it beeps to let us know it has reached the set temperature...but it does this about 5 to 10 minutes before it actually reaches the set temp.

Could it be the thermostat that needs replacing?

Second item is the internal door glass. It cracked the other night when some cold water came into contact with the hot glass. I see the glass part is about $37.00. Do I need anything else other than the replacement glass once I take the door apart? (Insulation, etc)