I mean, it is entirely plausible that they are upgrading a lot of parts to bring it mechanically up to date with the latest mad house models. Which I guess you could do without replacing the actual drum itself.
If this is true and it is a big if, staying statements like 'they will never learn' is slightly unfair. If it turns out to be true, this along side all the current investment going into the park right now shows serious amounts of cash are being spent, much more than under the Merlin PLC days, cash that is attempting to right the lack of maintenance that was given over the years.
Given that, it is entirely plausible they will maintain and look after their equipment better after the 'new' Merlin have spent so much money in bringing aging equipment up to scratch. But, as was said previously, the ride has been run hard all of it's life, this would be inevitable one way or another eventually.
Skyride is one of the oldest large scale ropeways on the planet, the same could be said for that. Large investments would be needed at some point, especially given the astronomical operating hours both attractions have accumulated.
You can maintain equipment to a really high standard, run it really hard (as is most certainly the case with Hex) you will end up in the same boat as if you had not maintained it properly.
The part about Vekoma not wanting to touch Hex could be true, this is usually the case when parks carry out large scale repairs, which can be for a number of reasons. As then, if it breaks again, the liability could be pushed over to Vekoma, when in actual fact the root cause could have been caused by something done internally. Much easier for the OEM to refuse to touch it, this happens in many, many different industries.