Knots

Make sure you are properly tying the Polamar knot - I never have a problem with it.

Maybe try a short flouro leader, the line could be gettin chaffed or wrapped up. Flouro is more abrasion resistant and less limp. I've also never had an issue w palomar knots, but have had fraying issues.

Why not just use weighted hooks instead of using the bead and bullet weight. That would eliminate the slippage of the bullet weight on our knot completely.  But what do I know its just a suggestion .  The fish have no trouble picking up a weighted hook.

Could be an issue with the bullet weight. Do you peg it? Not all weights are created equal. Some have sharp edges from inferior lead pours - they can easily cut into the line. Check these gnarly looking things:

 
That has frayed / broken line written all over it after repeated strong hooksets. I prefer a weight with the plastic insert in the center so line will not be in contact with the metal. Gambler makes good ones, but in time that plastic insert will eventually crack at the bottom - usually after many hooksets:

I use these screw-in weights often on worms. Another advantage of the screw-in, you pull your plastic past the eye of the hook and it can actually protect the knot, should the weight come loose.
 
I now use a bobber stop to protect the knot when I don't want it pegged. These really became popular for punching. Simple to add to your line after the bullet weight and before tying the hook. They're cheap, usually only need one per trip for my t-rig rod:

Also, make sure the loop you put your hook through is not twisted, and make sure the loop cinches down above the hook eye, not around it.