1. Is the topping lift a custom-built part or is there a vendor (somewhere?) that sells one off the shelf?
It's just some (relatively light) wire with some hardware at each end. Nothing overly sophisticated about it.
2. Assuming I can find a new topping lift (or have one made?):
Is this something that I can replace myself or should I have the marina service guys do the work? I have a boson's chair - I might be able to persuade a couple of good friends lift me up to the top of the mast so that I could replace the topping lift?
Unfortunately, I do not recall how it's attached at the masthead. I'd go up and take a look, then decide. If I was on vacation, I'd take this as an excuse to go up and look for you. Alas: Vacation's over
I seem to recall a thimble. I'm guessing the wire's crimped around a thimble and there's a clevis pin up there or something. Sorry: That's the best I can do, short of going up Abracadabra's mast.
would never pay a yard $400 for such a job.
3. Is there an upgrade to the original design?
Like I said: It's a simple thing. I'm sure it could be upgraded in many ways, but I can think of few that would make a lot of sense. Ours has a small 2:1 set of blocks on the end, with a built-in clam cleat, which allows us to leave it attached when the sail's up, then haul it up higher when the main's down.