Hi Ive just picked up my second blaster, i bought it with this noise for a good price. The noice comes from the top end, and is a loud tapping noise at idle, less noticeable at higher RPMs. Ive done some research on this forum and have come to the conlcusion that its either piston slap, wrist pin bearing, broken skirt etc... I pulled the head and found quite a lot of play in side to side with the piston in the bore and I am able to twist the piston. I also see some abnormal wear in my opinion on the cylinder itself I am not sure if the play is normal and should tighten up when the engine warms or if i got a rebuild in my near future. I attached pictures and a link to a video of the head, and cylinder.