Apologies ahead of time, my first post will be a lengthy one...
Interesting subject here. As someone who worked on the Eiffel Tower ride for several years during college, I can vouch that Shaggy's version of Tower Johnny (not sure where Tommy came from) is the most accurate.
The only difference I have heard from that version is that Johnny did not fall but was attempting to "surf" on top the elevator as it came up. Upon jumping on the top of it from the 50' level, part of his body was hanging over the side (upper part/torso??). The elevator rides about 4-6" from the steel cross-members lining the shaft...with the elevator travelling at 6 mph and the cross-members placed every~10 feet, this gave him no time to crawl completely on the top before being dismembered. Other than this variation, Shaggy's version is completely accurate according to what I heard over those years.
Tower Johnny was a frequent and openly discussed/joked about subject amongst the crew. It was rumored at that time that he haunted the area around the second lift of The Beast. However, our crew was witness to several unexplained "maintenance" issues during my time there (elevators stopping for no reason, doors opening, etc.). We would sshut down and the blue shirts would come out and put oil on something and say "it's fixed now"...nobody knew what the h*ll was going on with these occurences.
Suspending my disbelief in ghosts, I do think that Johnny is a kindred spirit and does not mean harm. Short of that, I think it was all just fun and games to make 12 hour-sweet-hangover-misery-filled days go by faster.