Thanks for the offer. I've posted on the tech help forum set up by the server; they don't seem to want to offer any solutions for this other than to insist that all the forums they host should go to a "log-in" system where everyone would have a screen name and password.
I'm not convinced that would be popular, and while I like the idea of forcing "real name" access, I think forcing the administrative step of logging in and "presenting credentials" would just dissuade people from using the forum. So I think the occasional ad for Cialis is preferable to that. For now I think they're easily ignored, and I can continue to sweep them clean periodically.
Unless there is a large outpouring of support for a log-in system, but I don't see that happening. I think it's important for 'guests' to be able to post their questions here unimpeded as I see it as one of the main functions of the forum.
I've blocked a couple of key IP addresses, and it seems to have ceased the spam for now. If anyone finds that their ability to post on the forum has also been curtailed, please contact me at my email address noted above.