[luke90]

bought a project car, was lied to about condition of car. need help diagnosing a gear selection issue.
Car:2006 e90 318i msport n43
context: car is a non runner and i cannot start the engine until next week (flat battery and hpfp clogged) but these are not the focus of this post.
issue: with car turned off, car shifts into first and reverse, difficulty finding second, nearly impossible to go into third without punching it in, impossible to go into 4th, and 5th and 6th both seem to work but are loose and not as firm as my last e90 (318d).
what is/are the likely cause(s) of this/ what parts are most likely to be faulty? the gear shifter is aftermarket (sparco) and the previous owner modified the car and is completely untrustworthy.

i am optimistic that he installed the shifter incorrectly but i haven't the knowledge myself to be anywhere near sure. i did not know about this issue and frankly wouldn't have touched the car if i had. i got it for a decent price and am willing to put some money into fixing it but i really hope it's not too expensive. i would be wildly appreciative of any help and will happily answer any relevant questions.