Crosley 515 Tuning Drive

I have a Crosley 515 with a broken tuning drive.
It consists of a celluloid(?) disc, which has cracked and broken, on a
boss 
mounted on the tuning capacitor's shaft, which should engage with a groove

in what appears to be a pulley, but could be a pair of dished washers, on 
the shaft with the knob.
I'm thinking of trying cutting a disc from a 2-litre fizzy drinks bottle
or 
an inkjet transparency sheet and gluing it onto the remains.
Does anyone have any experience of this, or better ideas, or a source for 
replacements or repros., please?
Martin.