Small Engines (Lawn Mowers, etc.): john deere lawnmower 180 fc540v, john deere lawnmower, rear pulley

Question
im trying to replace the  vbelt for the blades. the belt broke i took it to the store we measured and guessed a 5/8th 60 in. i tried toput it on butit looked small. there are two pulley. front and back. i dont see anything else for tension. it has a lever to engage the blades. i dropped that and put the belt in groove on rear pulley. the belt hooked the front pulleys center bolt leaving about an inch and 3/4 to make up. i know nothing about this stuff so i called the store asked their opinion. we decided on a 61. i put it on with a screw driver forcing it over the front pulley while turning the belt it wasnt easy. i mowed for an hour then the belt came off. i went to put it on again and it is about two inces long. so maybe the first belt was right, but i dont think i could get that one on the same way. i tried to find belt sizes and info on how to change this mowers blade belt, but i cant find the model # just what i put in the above and none of those lok like this. it has two pulleys front and back. the back pulley controls the blades (it has two blades left and right) pulleys. one on the left, one on the right and a center  pulley which i assume keeps tension on the belt that controls all three.

Answer
I looked up JD 180 and found the following belt lengths/part numbers.


   Belts  Mower Primary (1170 Mower 46")      M91147  Price it  Check Inventory   
   Belts  Mower Primary (970 Mower 38")       M77988  Price it  Check Inventory   
   Belts  Mower Secondary (1170 Mower 46")    M84136  Price it  Check Inventory   
   Belts  Mower Secondary (970 Mower 38")     M82462  Price it  Check Inventory   
   

You can Google the part numbers and find belt lengths.  Do you still have the owner's manual?

Eric