Small Engines (Lawn Mowers, etc.): transmission problems, running gears, riding mower

Question
I have a poulan 15hp riding mower with a 38" deck. model po1538, manufacture ID# po1538d it has a 5 speed transmission. Age is about 5yrs. Shifting has been getting harder the last couple of months. Lately it will seldom go into reverse. What can be done to remedy this problem?

Answer
It sounds like shifter key problems.  These keys run on a shaft inside the gear and as you shift the transmission moves the  move from first to second etc.  the best way to repair this is remove the transmission split the case clean out all the grease inspect the input gears to running gears to shifter key etc. for wearing damage replace what is worn or damaged.  This usually comes from shift on the go.  the only way to prevent it is to fully engage the clutch between the gear.  hope this helps.