Hi Troy
I had PGM3 issues with my MC21 and was reliably informed that a PGM4 is not the answer. You will find PGM3's on eBay for around $200AUD (that would be about 5 pounds at current exchange rates). I was looking for ages and suddenly a whole bunch turned up at once from Japan. Stuck one in and bike started second kick and everything worked as it should. If you have a bit of time to wait you'll get one guaranteed.