I have an old Siegler heater and haven't used it much for some time so trying to figure out if it is operating normally. When I turned it on initially, the indoor temperature was 40 degrees and it went through several cycles - burner on full blast, then fan cycling on/off until the house was warm. I heard the unit go through several cycles last night. Today the burner has been burning at a low level all day - see pic 2 below - and wondering if this is normal?

I called 2 local heating and cooling companies - one said that the gas valve is starting go bad and that the burner should shut off completely between cycles and the other said the burner is supposed to modulate and go down to a low level in between cycles so it is operating normally. If I turn the temperature control knob below the current setting, the burner goes out completely and if I turn it up to a higher setting, the burner goes from the low level to full blast. Both heating companies said that it isn't dangerous to keep using the unit as is, with the first company just saying the gas valve could go so I might want to replace the whole unit.

I am trying to avoid contact with people during this time and normally would have someone come out to take a look but hoping to get some advice. Under normal conditions, I would be more inclined to replace the old unit completely but would rather wait if possible until things settle down. Thank for any advice!