Window regulators - Looks like they are an inherent weak spot

To be honest there was no mention of how the water ingress happens, but I'm positive that its nothing to do with window tinting or work done that involves stripping the doors - my car has neither tinted windows or had the doors stripped. Aftermarket window tinting in the UK is fairly limited (we don't get that much sun ) with the majority that is done tending to be done by the kids - not your typical 124/MX5 owner. - I dont think I have ever seen a latest gen MX5 with tinted windows.

You could open up the regulator spool (its not the motor that's the issue) but the spool is under tension and if that tension is released ( which can easily happen) its a bitch of a job to re wind it with the correct tension. When I replaced the drivers side regulator a few months ago I opened the old spool to see what was going on and the cable inside had significant corrosion inside that had led to the cable fraying and eventually snapping. At the time I hoped that this was a one off, but clearly not

To be honest chaps I think you are barking up the wrong tree regarding high pressure car washes as the culprit. Both my regulators have now failed within 6 months of each other, yet you could count on one hand the number of times I've taken my car to a car wash with uses high pressure washers as I'm concerned about the causing water leaks through the roof. On the odd occasion I've used them, the water jet has been at 90degrees to the window glass and not pointing down towards the weather strip. No doubt however we wash our cars ( unless its waterless and these seem to cause more problems for the paintwork) it puts more pressure on the weather strips than natural rain, but Ive never had a regulator fail on any other car in 38 years of car ownership and that has included high pressure car washes on hard top cars.