Another option is always......
the forum.
First of all, put your location or general location (watch out for stalkers!) in your profile. That’ll help.
Someone on this forum could fab you one.
Someone on this forum could sell you a genuine OEM part.
Someone on this forum could assist you step-by-step in fabricating your own.
That forum member could be 500 miles away ...or your next door neighbor.
If you find yourself in dire straits over this predicament with no easy way out, maybe in the future you’ll be wise not to spend money on long-out-of production go karts from defunct factories, eh?
Buy new, man. Buy new!