Ideal 61-734 Current probe plastic knob replacement

[rfengg]

Have a Ideal 61-734 Current probe ; unfortunately the tabs on plastic knob which sits on the switch selector has been broken  due to which I cannot get the plastic knob to sit and lock on the selector switch .

I have attached pics of the offending parts.
Is there anyway I can get hold of a replacement for this plastic knob?

Any mods you guys can suggest to get this to sit on the selector switch; I did contact Ideal and since its an old model, they dont have any replacements