Coolant expansion tank cap leaking?

Second flight completed yesterday and this morning I confirm problem resolved without the need to buy any replacement items. I’m convinced it was my existing overflow tubing as when I removed it to inspect it, the end attached to the expansion tank barb came off quite easily, it was stiffer and less pliable than the remainder of the tubing, and had no clamping mechanism at the tank. Oops. Clearance is so tight under that tank barb conventional clamps won’t work. So I cut back both ends of the tubing until reaching pliable material, reattached the tubing, added lock wire clamps at both ends (lock wire will fit up under there) and topped off the coolant in the expansion tank. Working as designed again. Still need to find replacement tubing for next Summer’s five year rubber renewal.