5th wheel brakes and breakaway switch

On my maiden voyage return trip, the "breakaway pin" inadvertenly falls out. I thought I was paying attention, but it seems to jerk quite a bit anyway so I didn't notice for maybe 30 miles. (don't know) This is on a 2010, 35 ft LZ 5th wheel. I'm pulling it with a 3/4 ton Power stroke diesel. I guess maybe the brakes weren't adjusted properly because 1 shoe was completely gone, but the other 3 still had almost 1/2 the pad left. Wierd. I plan to replace all 4 brake backing plates, but only 2 of the drums, others look fine. SOUND OK?
Also, should I be able to pull the breakaway switch pin out by hand? I cannot. Maybe its supposed to be really tight or it's melted into place.