Got lucky this morning and picked up a Roland MC-505 for £100. Apart from a small chip in the paint on the very tip of the corner of the body and a 1 cm fine scratch, it in pretty damn good shape. It was, however, filthy. Stripped it all down. Cleaned all the contacts. Gave it a good service and now it's all perfect.
What a great machine too. Has some really superb sounds and plenty of vinatge stuff in there too.