1990 sidekick mt tranny problem. wont shift.

ok, its a 1990 sidekick with 292,000km drove out of lordco the other day, shifted fine into second and went to grab 3rd and wouldnt go into gear, also wouldnt go back into second, truck struggled to get into first at a complete stop and wouldnt grab any other gears, (shifter wouldnt engage) the shifter felt a bit sloppier then before but it drove fine in first and at one point i got it into 3rd (thank god, people dont like getting stuck behind someone doing 30km/h in a 50...)

pulled the shifter boot, knob, inner boot off and all looks ok from there, no abnormal things underneath, full of fluid (maybe a 1/4 low...)
got the truck back to my house and into the driveway and its now better (getting 1st, second, sometimes 3rd, 4th, and rev (didnt try 5th)

could it be my tranny is F*cked or is it a simple thing that im not seeing?

Check the slave cylinder's fluid level, make sure it is up where it should be.

Have someone else look under the vehicle while you press on the clutch pedal and make sure the slave cylinder is moving all the way forward, it may just need to be bled.

truck is cable operated, clutch cable nice and tight.