NOS tubes got bent in Ming-Da MC-7R preamp

I purchased a Ming-Da MC-7R preamp directly from the manufacturer. It sounds pretty good but I usually use other amps (mostly integarted amps).

The stock tubes are Chinese 12AU7 (2 pcs) and 12AX7 (2 pcs) and one rectifier. When I wanted to try some NOS tubes with this preamp (like Sylvania 7025), I could not insert them into the sockets. When I used some force, I managed to insert them halfway only, so I pulled them back. The pins of Sylvania tubes got bent. Luckly, I have a tube flattening tool and I managed to flatten them.

Then I noticed that the pins of all stock tubes are bent (perhaps, the tube sockets installed on the preamp were faulty, and the Chinese preamp tubes were somehow "adapted" to them and got bent.

I put this preamp in the drawer and don't use it, but if I want to sell it, I will have to warn the potential buyer of this problem.

Do I need to replace the stock tube sockets of the preamp? If so, which ones? In this case, will I need a tech?

Any thoughts?  

Stick the original Chinese tubes back in and warn interested buyers of the problems!