yeah intermittent problems are difficult and in the end you have to trust in their judgement. however, similar issues have been reported on here about unresponsive pads and afaik has been resolved by reloading software etc. in the end, if it can’t be replicated in test mode then it’s a software issue. you could do some extensive testing in test mode by leaving the machine on for a couple of days and hitting the pad every time you walk past it! there’s no voodoo involved, it’s either a faulty pad, a bad solder connection or a software problem. it might pay to do the test, or you surely have to send it back and that may be more painful!