[Windflier]

Try the Kroil or liquid wrench or PB Blaster and gentle patience. It is likely the threads in the aluminum will come out with the screws though and you’ll have to drill and tap new threads or use a helicoil to keep the same thread size.

Thanks for the very informative reply. That's very helpful

I've already removed some zinc alloy bolts from the aluminum block, and they came out ok. I'm just crossing my fingers that some high quality penetrating oil and patience will do the trick for the steel machine screws, too.

[Sequoyah101]

quite welcome. You’ve had a lot of good suggestions from others. Seems like most times I work on my old stuff there is always one nut or bolt that just wants to be a problem.