I wouldn't be too worried about the excess friction in the gimbal. The excess friction would cause high drift on long flights. Something that you will not be doing.
The main priority is to get the unit to turn on without smoke coming out :-)
Looking at the pins on the rear end, they look okay. The main ones to worry about are the power and ground pins, they should be clean.
FYI - the top rear port (J3) is a test plug for the workshop.
FYI - I'm also trying to get my posting count up as I am unable to post pics until I have at least 8 posts on this forum. :-)