I have devised a solution that uses off-the-shelf rollers and will fit to the bow roller of my 40.5. I suspect that the same solution will work for many of the other Hunters of a similar size.
The biggest problem of replacements is that the available rollers either are the wrong design, material, or the dimensions of width, diameter, and spindle hole size don't match what is required.
Phil at the SBO store has my solution but I don't think he has had time to put together a solution "kit", and I am not 100% sure that it will work on the other Hunters without knowing the dimensions of width, diameter, and pin size.
Why don't you send him an email and ask about it. I want to support the store that provides this site so Phil has first dibs on providing the replacements.