No suction with shop vac?

i have a shop vac ive been using for a couple days, a "RIDGID" one,its was working fine,but then i decided to take the filter out because alls im doing is sucking up rocks out of my gr **THERES ALOT OF ROCKS TO BE SUCKED**anyways after i took the filter out,it still worker the same tight? then today i use it and it BARELY sucks any rocks up,and when it does it keeps them at the tip of the hose,so if you shake the hose,they fall right back out,theres like no suction at all,ive checked the hose,which isnt clogged,i checked the inside,all good,i took it apart,nothing clogged,i even put thie filter back in,and it still dosent work proprely,also,it has a really high pitched sound and doesnt sound right,my dad keeeps telling me to fix it but i have no idea whats wrong with it,and he wont let me buy a new one either so.... HELP!!!