Have you lubed the gear shift pivot? When these dry out down shifts become tricky. Just pop it off and pack with grease. Some guys fit grease nipples.
Done my one twice in around 40,000km.
Yes, forgot to mention that. Shifter shaft cleaned and lubed. My buddy had his stick so bad it quit shifting while we were in Utah. For about 12 hours we though the trip was over until I put some motor oil on the shifter.