I have an '07 F-150, 4.6L, 5-Spd manual, that has become increasingly harder to shift. Additionally, I sometimes have to really force it to get the trans into 1st gear, from a stop...For lack of a better description, the trans just seems "notchy," at times....This problem is somewhat intermittent...Is this a synchronizer issue, or something else? Truck has 40k original miles

 

Is it only hard to get it into gear at a stop? If so, it's probably a sticky pilot bearing. Could also be a clutch that needs bleeding or low fluid in the tranny.