Did you by change out the stock freewheel axle to a chro-molly axle? If you haven't, I strongly advise doing so.
The stock axle on the LandRider bent and I changed it out to a chro-molly axle which fixed the axle issue. I latter went to a Staton Inc hub because I also wanted a double walled rim as well on the LandRider.
Well history has repeated itself. I'll be doing a thread of this soon. The stock Sidewinder freewheel axle has now bent.
What caught my attention was some broken spokes; 4 total on the freewheel side. So now I have ordered more spokes and a chro-molly axle.
As you can see the bent axle was causing the back of the 34t sprocket to rub the spokes. Thankfully I spotted the broken spokes. Otherwise the next ride probably would have encountered a wheel failure. I don't jump curbs or ride over bumps hard either. The thing is often you can't even tell the axle is bent.
My other advice would be to change the Shimano Tourney rear derailleur out to a Sram X4. Of course you'll also have to get a Sram shifter as well.
We're all born ignorant.
A fool never learns from their mistakes
A smart person learns from their mistakes
The truly wise learns from their mistakes of others