I had the dreaded motor failure a couple of weeks ago on my Z4MR!
Put the roof down and the GF said she thought the roof went down slower than normal, but I can't say I noticed, but to be honest, I wasn't really looking. Anyway, it went down, then wouldn't go back up again. The latches still worked, but the roof didn't want to budge. After putting it up manually, I searched the forum and found the old posts from Bowser134 (Ross).
Luckily for me, this guy was 23 miles up the road, so I got in touch through the forum and managed to book my car in for the much more reasonable price of £580, using a brand new BMW motor that comes with a two year warranty.
I drove to Ross's today, left him with the car and he dropped me and the GF into his local town where we had a meal and three hours chilling in the local pub.
Ross showed me the old motor and it wasn't actually that bad, but definitely corroded. He said quite a bit of water came out when he cleared the drainage channels out.
Anyway, I now have a nice new motor, clear drainage channels and most importantly, a roof that works.
If anyone else needs this done, I can only say that I am more than happy with the work Ross did and wouldn't think twice about using him again, really decent chap.
Mike