I'm guess you would be a good person to ask. If the zippers on a encloser are starting to break and it's really stiff to zip can they be replaced, and how hard is it?
I know 0 about sewing and process!

The zippers sure can be replaced. I do it all the time. It's not hard but you need a machine capable of sewing through many layers of fabric. Also you need to mark the start and ending point etc.

inaforty - thanks for the information on the sewing machine brand.

Sweet Mary! I just went to the Sailrite website and they aren't cheap. $3500 to $5000 for what looks like a comparable model to what you mentioned.

Yep,
The good machines aren't cheap. You can do a lot of stuff with the smaller machine but it's more work and you will likely get skipped stitches and damage/scratch clear vinyl due to no working space. Some of the bigger panels are just not possible due to limited under arm space on a smaller machine.

The materials aren't cheap either. I just started using life time thread. An 8oz cone of thread (about the size of a good coffee cup) is $129.:oh:
The 12oz Stamoid used on many of the bigger sport fishers is $30 a yard!

I stay busy sewing due to the fact that it's not my full time job.
I don't have to charge for all the overhead (heat,building,healthcare,retirement,etc).