Nick Cat wrote:
Unfortunately this is close enough to true to rule. It might be that the
machine is simply out of its environmental rating, but either way if it's
decades old you're financially best off replacing it.

+1. A freezer that can't cool to -20C at room temperature (~20-25C) is
knackered, and will be thrashing itself trying.

Fridges can often be picked up relatively affordably on ebay when someone is
remodelling their kitchen and needs it gone ASAP. Not sure if the same
applies to chest freezers, but there may also be commercial ones going
spare. You might be able to pick up a late model for relatively little
money.

(also when you account for what Kingspan costs)

Theo