Thanks Miriam for your reply.
I completely forgot about how the lever would adjust the stitch width for the zz stitches! So thank you for this. I have tested the zz now and it sews the way I want.
The machine is in perfect condition, well oiled, all the knobs working and the tension is perfect. I think it was well loved by its previous owner.
Yes I saw before I purchased that the g model can be put on a treadle. If I come across a table or cabinet I might give it a go. It's pretty hard to come across tables in good condition over here that don't cost a small fortune. The threads in here are a great resource.
I picked up a Singer 28k today, need to have a look at the threads in here as I've never seen a vibrating shuttle in person before!