Incubator insecurity

Check your thermometer?

Do you have another one you can double chek with?

I have one of these. I think it works ok, BUT maintaining temp and humidy while holding the lid off to manually turn 16 eggs (actually usually onl fits 12 of my girls' eggs) proved a problem. I have had very good hatch rates though. The light kinda goes on and off all the time.  It only takes mine about an hour to reach temp, but I usually leave it about 3 hours for the humidity.

Dont despair, it also makes a PERFECT brooder for the last 3 days of hatching, when you stop turning. It has a nonslip grill, is the easiest to clean, and has reasonable resale value. Maybe you could save up and get an automatic one later, and use this one as a brooder.