Link here, Maura 

I honestly don't remember posting it (old age, maybe ) but I hope this helps !!  

Good luck.

I could do with you in my house, it takes my hubby a month to eat a jar of marmalade, and I don't like it, but I have all these recipes I want to try and a cupboard overflowing with marmalade so daren't make anymore

Sometimes when a soft set appears after an initial good set, it could mean that there is an enzyme at work breaking down the pectin structure. This could have come from something that was not deactivated enough in the cooking, or it is a post boiling contaminant like a yeast or mould from the air.

Industrially I have seen gels do that in other products- and sometimes it is nothing you would expect that has caused that - I once had to ditch several thousand litres of a thickened milk product because there was a minor ingredient in the formulation that was supposed to prevent something else happening that caused the thickener to shrink and give up its liquid again, and the whole product went thin. But an identical second batch using the same formulation made the same day, was perfectly OK the next day- I think that is an example of Murphy's law or something.

As long as I can spread it on my toast I am happy. I just love homemade jam and marmalade! I am currently using last years blackcurrant jam that you need a pneumatic drill to get out of the jar. Masses of blackcurrants in it and great flavour.