You are undertaking a noble cause. This laptop originally ran Win 3.11 with a 75 Mhz processor and 500-700 MB hard drive.
You will find system info here: http://bitlink.ca/Library/Toshiba/T4850.SPC
And support, downloads, information and troubleshooting at the Toshiba Website (UK) here: http://uk.computers.toshiba-europe.com/cgi-bin/ToshibaCSG/generic_content.jsp?service=UK&ID=Support_Homepage&cnt=GENERIC&key=Support_Homepage&banner_id=0000004e80
As above, I think you probably have a loose connection, but you could try conditioning it on the porch for a few days.
I take it the airing closet is no longer available?
BTW - do you have a credit card type memory card? If so, make sure it is properly in place.
Dell