Yes, I think the last two replies have the answer. The knob on the bed by the pillar is the stitch length regulator, it is set all the way to the left, so the stitch length is probably at nought. Have a look to see if the teeth move when you turn the wheel, then put the knob all the way to the right and see if there is a difference. Run a piece of paper through the machine with the knob at different positions so you can compare the stitch lengths.
This is like the stitch length regulator on my old Vestas and Frister and Rossmanns. On one of my machines it was so stiff it took me days of oiling it above and below to work it free.
Let us know how you get on!
I don't think it is anything to do with dropping dogs.