My 1963 CJ3B used primarily for snow plowing. Last winter I noticed that while engine runs fine it doesn't start moving quickly when disengaging clutch, & moves sluggishly. I assumed clutch problem, but in summer when I took it to my repair shop they said didn't see anything wrong with clutch. This winter again plowing snow and same issue observed. Doesn't like going up even a short incline, doesn't start moving immediately when I let up clutch. Soon I'll be taking it back to the shop for more analysis of the issue & hoped-for repair. Does this sound like need new clutch or clutch parts? or something else in powertrain? transmission? I think it can use transmission work, anyway -- pops out of 2nd gear. Or is this a combination of several issues?