Text from DHL saying the Glycol will be here after lunch so time to rig up a pressure test on the heat exchanger.
Encouragingly the catch pot had caught quite a lot over night which I think implies that the drips are just coolant on the plates held by capillary attraction and slowly falling lower - or is that wishful thinking !
So, firstly - open up one side of the coolant loop and find something to adapt from the 28 mm / 1" compression fitting to the 1/2" BSP output of my pressure test pump. The 'It'll come in handy box' furnished the needed bits.
Then opening the ball cock on the input side of the heat exchanger I pumped a fair volume of water, hoping to as far as possible force the air out and water in. Then, closing the ball cock I pumped the test pressure up to 200 PSI (system normally runs at 50 PSI) and will leave it for at least an hour to see if it holds, but so far so good.