When the FR-1012 IR Pre-heater is turned on, you might observe that at least 3 lamps do not illuminate.  When you look at the filament in the bulbs, they do not appear to be blown out.  This occurs becuase of oxidation that is on the contact that holds the lamps in place.

Re-seating the lamps typically solves this issue.

NOTE:  The reason at least three lamps do not illuminate is that they lamp array is wired into groups of 3 lamps.

CAUTION:  When removing or installing the lamps. be sure not to touch the lamp surface as doing so can cause premature lamp failure.