2000 Tacoma 2.4L 5 Speed Manual has trouble going into 1st and 5th gear while driving

hello tacoma community i have a 2000 Tacoma 2WD with a 2.4L and 5 speed manual regular cab short bed. I just got the truck it runs pretty good with 236,000 miles. i noticed that unless i am fully stopped i cannot shift into 1st gear. when going 5mph or 10mph+ i cannot shift into 1st gear. it is extremely difficult i tried once and heard a grinding noise. with the engine cold or warm it only shifts into 1st when fully stopped or going like 3mph.
another issue i’m having is shifting into 5th gear going on the highway. sometimes it makes a grinding noise going into 5th. i noticed if you are in 4th gear and the rpm’s are low, shifting into 5th is extremely difficult and will make grinding noise. if i am in 4th and the engine rpm’s are high, shifting into 5th is smooth.
i checked the transmission fluid, brake and clutch fluid. the brake and clutch fluid were a bit dirty. has anyone else experienced this issue? any help would be greatly appreciated. thanks