I had problems with bending L-Pins and walking L-brackets until I implemented ROBERTSUNRUS's solution of drilling holes in the pins and installing roll pins. Ever since I applied this solution the hitch has been trouble-free for me.
The L-pin's job is to act as a fence to keep the spring bar on the L-bracket. The problem is that the top of the L-pin usually rides on the top of the spring bar, and as the bar moves back and forth during turns, it binds, and applies forces that bends the pins and sometimes moves the brackets along the tongue. The roll pin keeps the top of the L-pin off the top of the spring bar, thus eliminating the bind.
This is exactly what Progressive's redesigned L-pin with the flip clip does.