Mat didn't survive the winter....

[golfdane]

Our mat has died (sort of). It seems, that it was stored under the wrong conditions, and is now useless as a vaulting mat. It has become hard (and it was hard last year, but not that hard).

Took the mat apart, and found out, that the core elements are massive chunks of foam. No channels or anything. I suspect, that someone replaced a damaged core once (years ago), and had no idea there was some reason behind the construction, and replaced with solid chunks of foam.
Now, if we were to replace the core, what density of foam would be appropriate? Could we possibly cut the existing foam and build the channels (preferably a dual layer of channels angled by 90 degrees)? At least to extend the usability until next year (when a new mat might be granted).