Topic: Firewire-to-Thunderbolt on MBP cuts out all the time (Fireface 400)

I have a FF400 which I've used on my MacBook Pro Retina since 2012 via a Firewire to Thunderbolt adapter. In the last year or so it's began becoming hyper sensitive. If it moves even a millimetre (no exaggeration) then it cuts off. At time no movement is even required - it just cuts out after a few seconds of activity.  Pulling my hair out!

I've tried resetting SMC and PRAM which seemed to help for a little while and then it all went bad again. The plug has always been a loose one (thanks Apple, £50 and you can't make a plug that fits comfortably in your own machine) but I'm not so sure it's a contact issue or else it would have always been a problem.

I'm currently on MacOS 10.15.2 but it's been this way for at least two minor versions of OSX/MacOS.

Anyone else experiencing this? Anything else I can try?