mk1 sticky gears

hi all
ive got a 83 1.8 gti and after around on hours use the gears become sticky
i done a much needed gear oil change last week and the problem still exists.
any ideas/help would be much appreciated!!

I've been driving mine daily since march and it's just started doing this changing 3rd to 4th. So yea any help would be great x 2

Could be heat from the down pipe affecting the selector rod/bushings?
 :dontknow:

My steering rack used to do that from the heat generated by the four branch until I made a simple heat shield.

Lubricate all the bushes. you can disconnect the linkage from the gearbox and retry, see if there still stiff. may bebworth doing it on a hot and cold engine to. Is gear selection good? if a bit iffy could be worth setting it up properly to