I have caulked the sides and sight windows on my Texas Hunter feeder. The damn things leak.
The feed clumped up, got down to the spin feeder, and jammed the spinner plate. That caused the motor to burn up. No warranty on “my negligence”. Not real impressed with them.
and here I've had mine on the pond for 6-7 years without any moisture issues.
I replaced all the windows/gaskets in the one that I bought from Fireishot and I haven't had any water issues with that one now either.
Of course it doesn't leak, I sprayed enough Flex Seal in it to seal a space capsule.
Always seal around the hopper windows. High temps in the summer, and low temps in the winter, is tough on plastic.
Another option to seal the hopper seam is HVAC tape. The hopper has to be clean and dry for that to work, but it works well.
Velcro a humidity gauge to the underside the lid of the hopper. You'd be surprised how high the humidity is. Often humidity, not a leak, causes the clumps.
Run your feeder completely empty after 3-4 bags. Use a stiff toothbrush, or a parts brush, to clean out all the corners. 2" flexible putty knifes work well too. Flat for the hopper wall, and on edge for the corners. Focus on the seam.
Don't feed the possibly mildewed clumps of wet fish food. Take it out, and throw it out to the raccoons somewhere other than where the feeder is.