Thank you so much for your response.
on further investigation I decided that it was in fact the upper thread that was being caught - wasn’t sure if it was catching on the bobbin case. I tried a few things including changing needle, thread altering tensions etc. then I remembered also ready somewhere else about doing free motion with the feed dogs up and stitch length altered, so thought I might as well give that a go too!
result is I had good success with this method and have managed to complete my quilting for that quilt
inhad decided that my machine also probably need a good service, so I will shortly take it in for a good service as well, and in the meantime I will continue to use with the feed dogs up and see if this helps out next time.
i think I will also give your paper stitching a try as well to help improve on my technique!
thanks again so much for your advice.