I just finished my incubator and am trying to adjust the temp. Have fan and thermo (used water heater type like shown in some of incutators in forum). I can not seem to get adjustment to hold. Light will go out when therm in wiggler shows 99.5 but cools down to about 97.5 to 98 before coming back on. I try a slight adj and end up with temp in wiggler 100+ before heat light goes out. I am so frustrated I am tempted to just give up--but I have a few test eggs due in this week.