Osram, Phillips, and Ushio all list their operating positions as "any", though maybe they would tell you something different if you called. It seems to me that the orientation simply doesn't matter with single-ended lamps. The crack on the base of your lamp is certainly not good news, but I would expect the lamp to keep on running for now. Eventually, the vacuum seal of your outer envelope will fail, and so will the lamp. You might notice a white buildup on the glass as the lamp gets worse.
As for greasing the worm-gear of your M18 focus drive, I would say go ahead, but be sure to use a high-temperature lubricant. It is possible that the squeaking is indicative of something other than corrosion of your focus drive. Perhaps the lamp-lock lever has been forced forward or backward by impact, maybe shipping. If that were to happen, the lamp carriage could become twisted slightly. When you move your lamp carriage into full flood position, does the lamp rotate slightly?
Edited by Brian Doran, 24 May 2018 - 06:28 PM.