the unit for sale
on ebay that you linked to says 80 II on the outer case rather than 80 E. It has 2 separate pressure vessels, each with a membrane inside.
My 80E is not in a case and it has a single
long pressure vessel containing 2 membranes. All versions use the same type membranes I think.
A seller would be crazy to let somebody dismantle pressure vessels to inspect membranes. They might easily damage vessel, membranes, seals
or spigots. Even if they didn't damage anything or introduce bacteria the unit would still need re-pickling.
Can't tell if the membranes are OK just by looking anyway. If they were dry though that would mean they're probably useless.
Repeated TDS meter testing of product water
with acid/alkaline cleaning
flushes between tests if necessary is the only way I know of to tell if the membranes are usable or can be restored.
It's not a quick or easy process. Even tap water
can destroy membranes.
I've only learned this from reading though - experts hopefully will correct me.