hi -

ask technicians in your near area.
all you need is an UV-burner (to erase your old eproms)
and do burn the new version with an eprommer.

before you erase the data you write down the specification and the slot
location on a paper.
then you SAVE the content of the eprom on HDD.

ask technicians in your near area (computer or electro shops)
they should know how to do and will maybe help you.
its not a big problem if somebody has the eprom machine and the UV eraser.