. Great news OP, I should have said that the threading is in at the top, over to the left and across really.
The manual tells you anything else you might need to know in a dull moment, including a bit on treadles.
I must confess that when I bought my 201 I wanted a treadle but it was such a nice example that I bought a hand crank. I could convert it but like it as it is. Then the Pfaff 30 came along when I was still looking for a treadle (it is electric), then a lovely table, the likes of which I hadn't seen before to put the Pfaff in.
I would still like a treadle
.