CDC (MPI) floppy drive

Does anybody haev a CDC/MPI full height 5.25" floppy drive? No, I am not looking to buy one, I need some information on how it goes together. I have one in an HP9826, it's fucntionally the same as a TM100-2A, but intenrally quite different. The area I am baving prolems understanding is the head positioner. The head carriage runs conventionally on a pair of metal rails fixed ot the base casting. At the rear right of the drive is a stepper motor with the spindle axis vertical. On that spindle is the metal drum of a taut band mechanism, there's alos the conventional taut band. That fits over a pin on the drum. The ends of the band have holes that fit over pins on the head carriage, the rear p[in being fixed to the carriage, the front one is spring-loaded to tension the band. So far, so good. Mouleded into the head carriage are 2 arms that extend to the right of the drive, past the taut band assemly. They seem to carry some kind of damper. And that's the real prolkem In my drive, the damer had oozed grease all over the chassis. I've stripped it all down and cleaned it up. What I can't work out is how it should go back together. The 'damper' consists of a weight made af a soft metal, probably lead. And a metal shaft, about 1mm diameter, that runs through a hole in the middle of this weight, the ends of which locate in the arms I mentioned. And that's all I have. There's no obvious place to put grease inside the weight (I've looked down the hole as best I an). If you put grease on the shaft, it's just going to ooze out again. Also, what keeps the weight in the right position on the shaft? It's considerale shorter than the space between the arms. Surely it shouldn't just flop backwards and forwards? Another odditiy. When I removed the tauth band, I notixed what appeared to be a plastic clip on one of the pins. More careful inspection showed it was an O-ring that had split. OK, I can get replacements. But why put an O-ring there in the first place? It's not going to keep the band on the pin, or anything like that. My thought is that this has been dismantled before, that the O-ring actually came from the shaft that carries the weight, and that there may be parts missing (Springs, washers, etc). Does anyone ahve such a drive and could at least tell me what the damper appears to consist of (No, I am not asking you to take it to bits, just indicate if there's anything on that shaft other than the weight, if there are any ruber seals. etc? -tony