Well found brora! (the threads) that took me back seeing all those old forum usernames (ah, those were the days...

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Hi javelin, as you can probably see from the links, the bumpstop fits directly above the rear axle, to stop the axle actually striking the chassis when the suspension is working to extremities.
Mine fell off a few weeks back.
The bumpstop is bonded onto a metal plate,and its common for it to drop off the plate eventually.
To repair, remove the plate, (two 12mm bolts i think) and give the plate a damn good clean.
I soaked mine in thinners for a few hours, although i,m sure brake cleaner would work just as well.
Then, key the inner face of the bumpstop with a bit of emery cloth / scotchpad / or wet and dry.
I used a bonding compound called Sikaflex to re-bond the rubber to the baseplate. I have heard that others have used araldite successfully.
I used Sikaflex because of its "rubbery" properties when fully set.
After the initial bonding, i left it off the bongo for a couple of days ( i wasn't using the bongo at the time ) with a fair old weight on the bumpstop, to aid the adhesion of the sikaflex.
When you are happy that they have fused together successfully, then in typical hayne's fashion, reverse procedure to removal to re-fit
(p.s., have a bunch of various extension bars at hand for the ratchet,the passenger side stop is trickier for access than the drivers side)