Have you checked for lint in the bobbin area?

The 99 class machine uses a 66 bobbin. I find those machines don't like real thick thread. I usually use a machine with
15 class bobbins for thick thread and large 18 needles. If you don't use the same thread on top and in the bobbin
you will have problems on most machines.

You need the book for the machine and must follow it exactly. The flat side of the needle goes to the right and you
thread left to right. Not like a previous post. The bobbin must also go in a certain way. Hence the need for the book.

You shouldn't need larger than a 14 needle for your project. New upholstery thread should work fine. But you will have to change your tension settings to get the upholstery thread to stitch right. It is much slicker thread than say quilting
thread.

Thanks quilterman, I'll go thru the manual and see if it has this topic. I felt,it should have been able to sew this cause my mnl made many things with thick fabric. You also brought up the threading. I think I've been threading it wrong, but never saw a problem till now. Will let you know
Again thanks

Sorry just responding, but I pulled the manual out this morning, checked needle placement, which was right, flat side on left. However my book shows it being threaded right to left. Giving it another try this morning.

Yes that's right. If the needles goes in with the flat to the left then it threads right to left. You always thread the needle towards the flat side.

Cari

Yup, that was the problem, needle in wrong.now she's sewing like a dream thru the thick fabric.