Do you have an operators/parts manual for your machine? If not, get the machine model and PIN numbers, go to the Scag website, click on manuals, find your machine and download the manual.
As has been mentioned, remove both of the V belts from the deck and spin each rotating component to determine which may be problematic.
To remove a spindle assembly, the blade bolt must be removed first. The spindle pulleys have several parts, the hub, pulley, key and two bolts.
The pulley is set onto the spindle, the hub is then set on lined onto the key, the two bolts draw the pulley up onto the hub and squeeze the hub securing it tightly to the spindle shaft. The reverse will disassemble the pulley for removal. Unless there is corrosion, these pulley components are generally easily removed. With the two bolts removed, tapping on the pulley will loosen it from the hub and it will drop down. The hub, unless there is corrosion, will usually come up and off. If not, then a two or three jaw puller can be used, but protection of the spindle top to prevent damage to it from the puller screw will be needed.
Measure the distance from each pulley to the deck top before removing them so they can be placed back in the same position.
The Scag operators manual has a maintenance schedule that includes the spindles which are to be lubricated with the specified grease at 40 hour intervals. The idler pulleys are a condition change item and any roughness, noise, radial or axial movement is cause to replace them.
The idler/tensioner pulleys have non replaceable ball bearings. The spindles have two tapered roller bearings that are preloaded against each other for smooth turning of the spindle at high RPM.
