Help! Sudden shifting problems

[Josh Kinsley]

My '93 SE-R with 120k miles has a new and perhaps serious
problem. This problem came on suddenly, although there is no
obvious event which caused it.

It has become extremely difficult to shift into gear from a
stop. When at a stop light, with clutch pedal depressed and
in neutral, the car idles fine. But when I try to select
first, it is very difficult. I can generally force it into
first. After getting the shift lever into first, (clutch
still depressed) there is a 1 second pause, and then a
*thump* is heard and felt throughout the car. I can then
release the clutch and drive normally. It is equally
difficult to select second gear while the car is stopped. I
can shift up and down okay while moving, though it seems
there is a slight increase in effort required to select each
gear.

Can anyone diagnose this problem? Is it the shifting
linkage? Any tips for diagnosis and repair?

Many thanks,
Josh Kinsley