These things seem to be hit and miss. Mine lasted about 20 miles in all, during which time the cable had to be replaced (comes under general maintenance so excusable) and then the inner shaft cracked where the lowest of the three holes is drilled (could have been downright bloody dangerous!) and the pin would not stay in as the hole was deformed.
Sent it back to the UK ebay seller but I didn’t mention I knew exactly what was wrong as I did not want them accusing me of breaking it while stripping it down. Came back to me quite some time later after a less than friendly (on his part) email exchange having apparently gone “to our technical department for a minor adjustment” The minor adjustment seemed to consist of soaking it in WD40, it was absolutely dripping with it. Took the rubber gaiter off, the shaft was exactly the same as when I had sent it back. Raised a PayPal dispute and got my money back.