I changed the blade mandrel from my 42 inch cut craftman mower, I need to put it back together I need a directions on how to put the spring and pulley back on also I damaged the nut on the pulley, What size is the nut. this is on the left side of the mower.

The belt is not routed properly of there may be a tension spring not properly attached. Check the manufacturer's website for instructions.

okay check see if brakes is on the mower, not the tractor but the blades of the mower deck if not then take belt off of the new mandrel side and try turning blade by hand. should turn freely if not mandrel is bad but unlikely. sounds like you changed wrong side mandrel I presume you have 2 blades and mandrels. or when you installed it back on. the belt may be bound up between a guide and pulley just kind of look things over before a tear apart. and then do your tear apart one step at a time then check blade to see if it turns does not seem serious you may have put belt on wrong, I have done it my self. hope this helps major note do not do this with engine running cut you hand off in a flash.

Is the deck too low or one side lower than the other? Level the deck side to side, front should be a little lower than back (about 1/4 inch). check tires for correct air pressure. Make sure blades are balanced.

sounds like you may not have the right mandrels making the belt to tight and it cant be left loose enough to allow the blades to quit turning.Otherwise you didnt put the belt back on correctly if it is around the tightener pully the wrong way that to will make the belt to tight

there is a star shaped, or other, pattern on the bottom of the mandrel which fixes it into the blade. this has stripped so the blade is freewheeling on the mandrel. if you cannot remove the blade bolt, I think you are going to have to remove the deck and take it to a fabrication or machine shop to have them remove the blade from the mandrel. then you buy a new mandrel and a new blade, at a small engine repair shop, put it back together. take a picture of the top of the deck before you remove the deck belt so you know how to put it back on after you have the new mandrel bolted in. if it is old you may just want to replace all the mandrels while you are at it. they are less than 50 bucks each.

There is no adjustment on the Craftsman mower belt tension. The tension is maintained by a spring. If the belt is to loose you either have the wrong belt or something is broken like a mandrel housing that holds the fixed pulleys in place.

Several things here could be the problem. Check to see if mower deck is level, measure distance on both side on a level surface. Check tire's for low air. If you've replace the mandrel's lately, some have a left & right side & if not put back together properly this will cause uneven cutting

when you put the new blades on did you notice if they were even with each other? the 42" decks have a tendency to "warp" inward on the left side. this causes the left blade to ride at an angle to the right blade - there is a tool to correct this, but not all shops have it - sometimes you can remove the deck, flip it over and wallop the inside edge of the left mandrel until the blades are even - a 2 lb. sledge works well for this

You dont have to drop the deck. Remove the belt first then hold the blade in place so you can loosen the nut on top of the pulley. after you remove the pully then remove the blade. There are 3 bolts holding the mandrel in place remove the bolts. Then pull the mandrel out from underneath the mower deck. There is a shroud that will come loose with it or it may stick from accumilated grass regardless it needs to go back during reassembly. When putting it back together the 3 bolts are usually self tapping into the new aluminum mandrel. Its much easier to put these in and take them out before you install the new mandrel as the bolts cut the threads.

Hope this helps

Brent

Either the deck is uneven or one of the blades are upside down