Sliding bench seat removal

[donboon]

I need to service my rear folding bench seat in a 2015 T5 California because it’s become very stiff to slide. I’ve removed the drawer but the torx screws on both inner side panels are solid. Already stripped one. Tried various methods, hammer to loosen, torque driver, cursing, nothing moves. The only solution I can think of is removing the whole seat and putting it on a bench so I can grind or drill the screws out to get at mechanisms.
I’ve worked out how to remove floor panels and can see the tracks are filthy. Moving the seat requires pulling the handle up as hard as it can go and even then some. Clearly the mechanism is either worn or stuck with dirt.
Any suggestions that might avoid all that pain?

 

[Rich20]

Removing the rear seat is not easy and surprisingly heavy so not for the faint hearted. The seat cushion can be removed (had mine re trimmed ) but not 100% sure how to remove it. Once removed you should have access to the mechanisms to see what is going on.