I discovered a few years ago that the #6 wire had a similar problem. I contacted STI and they sent a replacement at no charge.


I know there are fans of Magnacore, Kingsbourne and STI but given the performance I've had and the price I recommend STI.

 

Sometimes, not every time though, an 'Italian tune up' works wonders as the engines clog up with coke and crud. It's worth a try, take it out, give it the 'beans' in sport mode for 5-10 miles and then see whether the problem has gone.