Try setting your tensions the way Jamie Wallen recommends. It works for quilting on all machines, but is especially helpful for quilting on a longarm. Here is a link to his video:
https://www.youtube.com/watch?v=Q1mRhcquZTM
What type and brand of thread are you using? I have found that Glide thread (a trilobal polyester from bobbincentral, available online from retail distributors) is very carefree on the longarm. I would recommend purchasing just one cone and trying it out to see if it solves some of your problems.
What brand and size of needle is in your machine? Typically you want a size 16 or even 18 for a longarm. However, it also depends somewhat on what size needle your machine came from. I just took a class from Jamie Wallen and he mentioned that you should never skip a needle size (up or down) on your longarm, as longarms come timed from the factory for a specific needle size. You can move up or down one needle size from that without a problem, but skipping a needle size can require re-timing of your machine for that needle size. Probably not your current issue, though.
Here is a link to a Yahoo group for the Pfaff machines, including yours:
https://groups.yahoo.com/neo/groups/...ndQuilter/info
The above appears to be an active group, and you are likely to find some good help there that is specific to your setup.
Edit: Be sure to check out the links previously posted. It's possible your problems are related to your frame setup, and one of those links shows how to change it.
One more thing to consider. How tight are you winding the quilt sandwich? If it's drum tight, that can cause problems. Typically you want it loose enough that you can grab a finder that is poked up from underneath.