I also have issues with the tap tempo of my lt, i use it alot, pushing the knop and twisting it a couple of times seems to work for a while and then it starts to malfunction again, I also have to hit it fairly hard to work, had the same problem with my podhd500x, replaced the tactile switch abouth 5 times in that one.
now I found this https://goo.gl/images/46DLxb
midi tap tempo switch for line 6 devices.
ordered one yesterday.