Heat Tape Question

To those that have had racks for a while, how often have you had to replace your heat tape? I am about to have to replace heat tape in a rack for the 4th time in 6 years. Twice on the same rack. This time is the oddest one.

I went to pull a girl out last night and I noticed she wasn't warm. Sure enough the tub hot spot was room temp. The thermostat was on. So I reach in and discovered that the spot where the probe is was warm (it's on the side where the tape starts to feed to the next shelf) but most of the tape where the tub would be over was not warm at all. And this was consistent through the whole rack. So something is wrong with the tape and needs replacing,

I have had 2 tapes overheat due the probe dislodging and another just completely died. Am I just unlucky with heat tape?

That does sound like a lot. Is the heat tape recessed so the tubs don't slide on it?

Yes. There is a groove for the tape to be in. The ones that overheated warped in some places though and came in contact with the tub. But the one now isn't warped. It's just not producing heat.