Sorry I'm late, Steve.

Hope the marrow survived. The way I prevent getting mould in the end my marrow is to check it for sugar and keep it brimmed. It will get soft and with my first one I strained it through a tea towel then mixed some yeast with yet more sugar and stuck it in a demijohn. It went berserk for a while and then calmed down. Racking is very important for getting rid of sediment. Do it about three times over the course of it's fermentation and top up with water, I used bottled. It won't dilute the flavour. Keep it until it really stops and bottle it. You can get away with spirit bottles that have a screw cap or cork bung.  Leave it alone in the bottle for easily a year if not longer and you'll be rewarded with a fantastic warming winter libation.

I'm going to try chopping up the next one and covering it with demerera sugar to see if that's any easier than hanging it and making a mess on the wife's kitchen floor.

Good luck

Ps it doesn't work so well with courgettes odly