No red light on Octagon 10

[JSO]

Used an old Octagon 10 just a few weeks ago and successfully hatched some button quail.
Need to use it again, and although it’s warming up the red light isn’t coming on at all.
Does this mean the thermostat has broken, or could just the light component
have failed?

 

[sourland]

If it is maintaining temperature, it is likely that the light bulb has burned out.