Success! 
This thing is sitting here with a clean install of OS 7.5 just purring away! Lost the RAMDoubler app in the process, might have that somewhere amidst my vintage software, but there's now only 70.5MB on the HD with 688MB free space. What a surprise! As they say, 98% of the time it's a software issue, although a week ago I'd never have believed it. The quickly-fading-screen issue has not reoccurred since the J1 OS, so assumedly that was due to some wacky extension from the original owner. Now to find some disk utility & maintenance software and clean up the hidden messes...
This thing is sitting here with a clean install of OS 7.5 just purring away! Lost the RAMDoubler app in the process, might have that somewhere amidst my vintage software, but there's now only 70.5MB on the HD with 688MB free space. What a surprise! As they say, 98% of the time it's a software issue, although a week ago I'd never have believed it. The quickly-fading-screen issue has not reoccurred since the J1 OS, so assumedly that was due to some wacky extension from the original owner. Now to find some disk utility & maintenance software and clean up the hidden messes...