Normally parts are not available for purchase from Titleist but you might have your local pro or a major Titleist distributor contact their product representative and see what they can do. Another option is to use the Titleist Drihood Towel Bag Hood although they work better on stand bags while walking or on a trolley at an angle than tour bags upright on a riding cart. Good luck with it and hope you find a solution.

Have a look on eBay some nice seaforth ones or similar you could be lucky and find a rep but the odds aren’t great

I have a Seaforth as a replacement, Really please with it.

Very good access to the clubs without having to keep unzipping.