Small Engines (Lawn Mowers, etc.): rider does not want to shift from forward to reverse when running, tractor model, lawn tractor

Question
I have an old 1990 MTD/Agway Lawn Tractor
(Model 130-653f019) 12/38 TL
New Belts routing checked and fine   when the engine is off it shifts just fine but when the engine is running you have to rock the mower back and forth or force it out of gear also the parking brake does not seem to hold May Be realted?
any suggestions? found adjuster but not sure if I should adjust the clutch seem to work fine also checked and with the clutch/brake engaged the belts are stopped still won't come out of gear
thanks for any info
Don

Answer
 Hello Don:

 If you put New Belts on and it was Working Fine Before,  then Please Check the Belt Routing Again. If the Belt Routing is Correct, then the Clutch is Out of Adjustment. When you Adjust the Clutch the Parking Brake will Work also. There can be No Pull on the Transaxle Pulley from the Engine when the Clutch is Engaged.  Hope This Helps.

 Good Luck

 Respectfully

 John