Hi everyone !

new here & new to the subaru world . i recently bought a 09 WRX hatch back 5 spd with 50,000 Kms . i just have a few questions , i have put about 10,000 Kms on it & done a engine oil change(mobil 1 synthetic) & transmition/rear diff change(amsoil full synthetic) . i have noticed that going from 2nd to 3rd , i have to push the shifter as far up into 3rd as possible(not hard) just hold it there untill i let out the clutch otherweise it pops out & grinds...also going from 3rd to 4th its not as smooth as the other shifts....it slightly grinds....im guessing this is all not good . i do not bang this thing into gears or bag on it in any way . any one that would have some info on what this might be or steer me in the right direction to read more about what this could mean would be greatly appreciated . also , is there a site that i could find part numbers ? the passenger side plastic rock gaurd between the front bumper & front tire is missing & i would like to replace it . thanks again to everyone