95 sp impeller replacement/repair

[Kuhl39]

Hi all, just got a freebee 95 sp that had some rocks go thru it and now there is no bottom end power. Looked into the pump housing and impeller looks a little chewed up! Question....i attempted to remove the housing and better evaluate the impeller but the small cone would not come off to get to the shaft bolt! It spun around and thats all. Does this have to be removed to remove housing? Tried to remove skid plate but similar problem all screws removed and no movement. What am i doing wrong? Thanks for any help. Vic