Grank

to be fare within all my years of driving I don't think I have ever change a gearbox filter

Hi All hope your well So he we go I have a Bmw 1 series I currently having some issues with first gear it will goes in when stationary. The min I try to pull forward it jumps out of gear. So my thought was it was the slave cylinder how ever I went to my local parts store and he questioned if it was that . Which then made we question it. the only other systems are the clutch pedal doesn't always retract to high and there is some build near the gear rode "sorry no it's not call that" but unsure what its called everything works fine apart from that no noise from gear box . I have read on the internet that it could just need a fuild change is this a possibility or I am looking something more expensive ? please help I am going mad