A small clunk is pretty normal from what I’ve seen. Ive had 3 new boats in 4 years and everyone of them did it. When you take off from a stop with a decent amount of acceleration I always feel that faint … thud… I’ve also loaded the trailer up the hill once and witness the brake actuator/ neck walk out as it bled off its pressure. Was a pretty intresting thing to see happen live. I would be its normal what your feeling plus a bit of play in your reciever/ pin.