Thanks for taking a look at it, Anton. I think the problem was that maxima.asd defined a nonstandard place for .abcl files to be written, and then ASDF didn't look in that place to load them. At one time (couple of years ago) it worked, but I guess ASDF has changed since then. No problem there. I've figured out how to make it work again, which I posted in another message.
best,
Robert Dodier