I have a Des I with many, many miles on it and have never had any problem with it--but it does sound like maybe the thread cutter mechanism is stuck with the needle down. I would turn the wheel toward me (maybe have to force it just a little bit) just to get the needle up, and then thouroughly clean around the bobbin and under, and especially around the cutter when it comes out. If that doesn't do it, I'd be on my way to the best repairman I could find! You spent too much $$ on that not to have it completely checked out.