I recently purchased a International 574 gas tractor with fender headlights. I need to replace the 2 floodlights mounted in the fender. Do you remove the 4 phillips screws in the front to access the headlight sealed beam lamp or do you remove the 5/16 pan headed slit truss screws (2 on top and 1 on each side) and take out the whole head light assembly. The 5/16 slotted screws are rusted in and not releasing. I have tried repeated spraying with Kroil around the 5/16 pan headed screws but they show no sign of releasing. I have brought a impact screwdriver kit with a slotted bit to use on these screws but fear damaging the sealed beam lights from the impact. I also thought of applying heat from a Mapp gas torch on the slotted screws but do not know what the applied heat might damage. Any suggestions as to removal would really be appreciated. Thank you