micra 1.2 1989 gearbox problem - oil change

Hello all,

Sorry for posting at both NG again, but my problem is aggravating fast.

In short : shifting out of 3rd gear is very hard, and causes problems to
shift into other gears. The stick is very hard to move and feels jammed. The
problem is not there when shifting out of 3rd gear when car isn't moving.

Likely causes have been suggested : clutch is not functioning properly, oil
is very polluted or just not there anymore, internal gearshift rods and
safing pins are not in good condition, external gearshift levers have too
much play and/or aren't well adjusted, excessive wear anywhere, ...

I'm heading for a new garage on tuesday, but I would welcome any
suggestions.

Other point : I don't find the gearbox oil drain- and inspection/oil fill
plugs. Does anybody on the NG has some ideas where to find them ?

MTIA, much obliged,

Regards

carl