I know this is an older machine. The reason I'm putting this up is that BOTH RIBON and the Service Manual incorrectly identify the heat lamps in the fuser. So if you're ordering heat lamps, know that both sources wrongly name the lamps and their positions:

Sub code (9). Evidence of a minor meltdown. Hot spots on the Sub Heat Lamp overheats the center of the heat roller while heating the outer edges. Discoloration inside the sub heat lamp matches the meltdown pattern on the heat roller. On the ohmmeter Sub heat lamp reads 2.9 ohms, then when tapped 9.0 ohms, then when tapped 7.6 ohms. Thermostats may become unreliable at fusing temperature, under load.

Replace heat lamps:
named "Center Heat Lamp": 6LH55336100, 600W, towards fuser exit, 4mm holes in both lamp terminals.
named "Sub Heat Lamp": 6LH55337100, 600W, towards fuser entrance, 3mm holes for both lamp terminals.
named "Side Heater Lamp": 6LH55338100, 300W, above and in the center of the heat roller, 3mm & 4mm holes in lamp terminals.
Center Thermostat: 6LH64641000
Side Thermostat: 6LH64642000

Clear the error in 08-400, set 9 to 0.

This has come up twice now, and since I didn't document it very well the first time, I couldn't be sure which lamp was which, and had to order all three. Maybe this will save someone some confusion.