Subaru Repair: 5mt not selecting gears easily, clutch master cylinder, clutch pedal

Question
I have a 2002 WRX manual sedan 5mt.  I have done 75 000 miles.  Clutch was changed at 30 000miles.  I have noticed the clutch engages suddenly.  I have recently started to experince difficulty getting the car into any gear while driving.  If i double declutch the car selects gear with no problem.  There is no grinding or any other noises while selecting gears. There is also no noises while depressing the clutch or while driving after selecting the gear. ALso if I am pressing the brake pedal the car will not select the gear until i release the brake pedal.
Some time if I really press the clutch pedal down VERY hard the car will select the gear. The clutch takes up very high.

Also recently I experienced a very unusual problem.  I was driving in 2nd gear.  I pressed the clutch in and tried to select 3.  It would not go into 3 or any other gear.  It would go from 2nd to neutral and only back into 2nd.  I drove the car back home in 2nd gear.  It would not engage any gear even with the engine off. I left it for 30 mins and the car was fine after that(i could get all gears).  I still can drive it and it selects gears with double declutching.  The dealer was not able to find any problems.

Is it likely that a failing clutch (bearing etc) is causing this?  Or could the master and slave cylinders need reconditioning?  

Answer
It might just be that the fluid in the clutch master cylinder reservoir has moisture in it and is boiling when it gets super hot.But also the WRX transmission doesn't hold up all that well if the car is driven hard from what i have seen especially if the car has any mods.So you could very well have a clutch and or syncro issue .If it was here we would start with inspecting/back flushing the hydraulics and go from there.

Justin
All Wheel Drive Auto