1989 Nissan 240SX speedometer and gear problem?

Nissan 240sx 1989, 87500 miles.

Hi im Steve. I didnt find any answer to my problem in the archives. Noticed something wrong at 2 different times. Bought this car 1 month ago.

1st problem: (i was accelerating and downshifting a bit that night)But at 47 miles/hour when trying to downshift from 4rth gear to 3rd gear, I first disengaged 4rth gear and tried engaging 3rd gear. But It DIDNT work. Even if I was forcing the gear into 3rd/4rth or 5th it would not work. I made it work by pressing clutch/gas and forcing it into place. After work, the car had trouble shifting in first gear but after that it went well I could go home. Gearing works ok but didnt go on road since that problem.
Only tried 1st, 2nd and reverse and it was working ok.


2nd problem: Speedometer doesnt work, cant monitor speed neither mileage compilation does work. It is still indicating 87500 miles. Tried another ''working'' speedometer but the problem is still there. Speed sensor on transmission maybe? If its the speed sensor on the transmission can you please help on how to locate it I have some difficulty on locating it with the chilton drawings.

Can you help me please? I would greatly appreciate it!

Steve