I just traded in my Memory Craft for the Skyline S5 and I love both of them. I got the Memory Craft used, and put a lot of miles on it. I use an old military metal desk for my sewing table and it is VERY stable. I never had a problem with vibrations even tho I sew very fast too.
My guess would be that this is an issue with your particular machine and I, too, suggest finding a new technician to work on it.