The rear wiper on The Volvo started to make a weird 'chattering' noise when operated last night (whether or not the wiper is on the glass), although it still works. Have I got a linkage or motor problem? I haven't got round to investigating yet, due to the rain ;)

Thanks for that. I had an idea that something was seizing up in the mechanism, particularly as I've never lubricated it. I'll know for sure when I have a look tomorrow :)

jp liddy 

hello james once you have removed the interior trim panel its quite easy to unbolt the shaft that goes through the glass then unbolt the other end at the wiper moter once on your bench the inner sleave shoud move easy but if like mine it had totaly siezed .i dont know how the moter kept going with plenty of wd 40 i got the centre shaft out of the sleave then a good cleaning with fine emery paper . try to mark the postion you take the arm of the moter end . if the problem is in the moter then i cant help .

Update: 

The morbid sound is coming from the wiper motor's wheel box, so I expect to be replacing the motor at some point in the near future. At least I got the chance to lubricate the wiper linkage and replace the high level brake light's bulb, which was looking very poorly :)