Defective lifting system, who pays?

I deal with this regularly and yes, with the statutory warranty on "things," the burden of proof shifts after 6 months.

Haven't the 6 months meanwhile become 12 months?

Doesn't one have warranty on construction defects? And a defect must have existed at the time of acceptance or have been demonstrably overlooked. The warranty precisely covers that. A device that has become worn out due to age does not, in my opinion, count as poor workmanship.

That can be seen both ways. With a pump that breaks within 5 years, one could assume that it was defective from the start. After all, pumps are not wear parts like, for example, light bulbs.

Isn't there a warranty for construction defects? And a defect must have already existed at the time of acceptance or have been demonstrably overlooked. The warranty exactly covers that.
A device that has become tired with age does not count as poor workmanship in my opinion.

But you are being generous there. A pump that only lasts 3 years and then breaks down can hardly be called tired with age. Pumps are built to run for 10 years; anything else would be unacceptable to our customers. If something like that happens more often, you quickly get dropped from the supplier list.