Ouch! That must be some tough durable fabric!
Hopefully just a broken needle.
I wish it was just a broken needle. The machine is actually quite suited to the task, when it works. I had it serviced once already, but the adjustment didn't last long. I think it's plain worn out.
As for the fabric, it's either duck cloth (white, yellow) or an outdoor polypropylene (blue, red). No rhyme or reason for one over the other, it's just what was in stock.
I have had a pair each of the red, in both duck and poly, in service since last April, as a sort of experiment to see if one is more durable/fade-resistant/easier to clean than the other.