I worked on a Swiss Char Mk 68 / 105mm mg that had been brought to the USA after being decommissioned. It had sat for years after sea water had damaged an electronic component controlling the transmission. The American owner had procured the correct replacement module but knew no one to do the work. I offered to trade the labor for a couple VW engine APUs he had in crates, never used. Replacing the module was difficult but doable. However, having sat for so many years, the engine oil and fuel left in the tanks required a tremendous amount of TLC. I was able to eventually get it all started and running again. The last time I saw it, he had sold it to some folks that had ruined it again by filling the transmission with the wrong fluids. I travelled to their location and drained the fluid, told them what they needed to do to fix it, and never heard back from them again.
I did 300 days on the old main battle tank and this is definitely the worst crew I ever saw: movement much to slow, loader does not know its procedure and is slow. Hits not observed and firing a 7.51 MG over 1000m is a joke... Wanna see these guys firing 12 shots in less than 30"!