Martin Logan ESL Expression 13a amp removal, woofer not working

My 13a has front and rear firing 10 inch woofers and one of my rear woofers is not working. It seems intermittent.  I took it out and saw nothing but when i put it back in, it worked!  For a while.

The amp is on the bottom and seems pretty difficult to remove.

Any tips or tricks to removing the amp?  It didn't simply unscrew and pop out easily like I wanted and I certainly don't want to damage any further.

Thanks!