How to purhcase a fully working HP41CX on eBay?

[Dol]

I have bought two HP41CX on eBay recently.
One described as in great condition and the other in great working condition.

HP41CX halfnut: (Canada)
Two of the expansion ports refused to work despite no visible corrosion. When the other two ports on the right (from the back of the calculator) are used, the calc will frequelty reset, and loose its time.

HP41CX fullnut: (USA)
Binding posts cracked and beep ever time a key is pressed.
No visible corrosion.

I mean, what do you have to do to get a fully working one?
I then took a flight to Sweden to retrieve my HP41 CV stored in the attic for the past 15 years.. Oh no. Of course the batteries had leakead all inside.. I got it up and running after some care.. But I am still looking for a CX
Any advice on how to get a a calculator which is fully working and according to the description? Does anyone have either a CX or a CL to sell?