Are you talking about the cotter pin?
It is a little tricky to get in and out, but I would not really call it a problem.
The Idler adjust is limited to 3 positions.
I think mine has always been in positioned in the middle/ with the pin almost straight up and down.

I tried the Schumo aftermarket idler adjust to get more positions, but did not care for it as it was too loose.
Mitosal sells their own version, which appears to be engineered better than Schumo's, but I don't know anyone who runs one.
So I use the stock Tamiya one w/ no issues.

I never had a problem w/ my 1st set of tracks that I ran for 4 years.
But my replacement set that I bought a few months ago, were a little 'sticky,' or too tight between the end caps and the links.
This caused them to bind a bit which mad a kinda popping noise as I drove.
So I took them off and massaged them a bit and put a little lateral torque on them by hand, which loosened them up a bit.