I had the same experience with my TravelPro bag.
Right after buying in line skate wheels to replace the inferior TP ones, and installing them, the handle extends and won't go back in.
While trying to get the handle out, I notice all the small plastic pieces in the bottom of the bag, just like the OP did.
Called and was told purchasing a new bag would be cheaper.
Looking at Briggs and Riley now. Also got 2 bags from stopoverstore.com.
Will never buy TravelPro again.