Hello, and welcome to the forum.

Have you made any other recent changes to the system, eg physically moving the kit around etc?

If it's been working normally and stable up until now, and this problem has just appeared, I think I'd get in touch with MrTechGuy (official Meridian service agent for legacy kit) here on the forum, as it does sound like a fault. Especially given the age of the 565.

Cheers

George