have you tried calling the HQ company in Utah? there is an 800 #...and their tech support team are wonderful! i was very unhappy after taking mine in to a local shop for cleaning and tuning...seemed like every time it went it came back with something wrong that was not wrong when it went, and they were just not (nice) to deal with...so I called Utah...they have been great, there have been a couple times when i have spent 1/2 an hour on the phone with them but i've always managed to fix what was wrong with their help and it is better than ever going to that shop...also, when my (mother-board) went out on my HQ-16 i called the local shop ... they told me i needed to "do an up-grade" to the tune of $750
I called Utah, told them what was happening...they sent me a (new) re-furbished mother-board for $100, including shipping and i had it in 3 days! (the shop had said i would be without my machine between 2&4 weeks) i have 'worn-out' a couple parts, had to buy a new bobbin case, but i think it is well worth calling them direct!