Rough GSR clutch / Rough gear shifting

I have a 96 gsr with 73K miles on it. Sometimes it's tough to shift into the gears. The odd thing is that it does not always happen and it doesn't happen with any gear in particular. Sometimes 1st gear is hard to get into. Other times it's tough to get into 5th gear and 1st is no problem. Then there are times that all the gears are a little tough to get into or all the gears are easy to get into. Very irregular "roughness." There's no audible grinding or any noise. It's just real rough to push the shifter into gear.

I don't think it's my shifting or that I'm not depressing the clutch pedal all the way down. I've been driving this car for years and have never had this problem before.

Tomorrow I'm going to change the manual transmission fluid and see if that helps. A couple mechanics I spoke to said this might be a good thing to try first. I'm not sure if it will help because I've kept up with all the scheduled maintenance since I bought the car. We'll see...

Any advice from someone with previous experience or knowledge would be great. Thanks.