Well some bad news, I got my A4000 out last week to install a new IDE HD and it is no longer recognising any Fast RAM. As you can see in the attached photo it looks like the battery acid is finally getting to some of the traces. I removed the battery when I first got the computer in 2012 and it didn't seem too bad then, but I guess I didn't clean it up well enough.
Hopefully this isn't the end, it's going to a trusty refurbisher on here for repair. Otherwise I'll be in the market for a new motherboard