Cruise control not working

[HPsauce]

Well I've had the cover off the electronics box with the controllers in it. Perfectly dry inside and no signs of any ingress of anything non-human.

Cover was a bit tricky as some of the bolts were corroded into the sockets, but it's gone back on securely and still works!
There was a bit of accumulated crud down the inaccesible edge under the windscreen so I hoovered and scraped out as much of that as I could. The seals looked OK though.

However once inside I'm rather wary. The main ECU is obviously outboard with nothing under it. So I left that alone.

The gearbox ECU is inboard and held down by 2 bolts at the front edge. I undid those so I could take it out but there was only limited movement and what appeared to be a release lever for the cabling was blocked by a fuse carrier. It wasn't obvious how to get it fully out - can anyone explain in detail?

Under that there is at least one more ECU but I couldn't see any label on the visible one. Is that likely to be the Cruise Control or is there something else to get out first?.