Happened to me for the first time a couple of days back. Cruising at about 60mph in 5th, light throttle (thankfully), and it just jumped out of 5th. Engine revs up to 5500rpm, and after a second of "what's that weird noise" I realised what had happened.

I know others have had this, but the search is down so I can't find out about it... So could someone remind me what was the cause of it? Is it a gearbox re-build job? I seem to remember it was something to do with a cuff or grubscrew or something working loose...

MY00 PPP btw.

Thanks
Richard