Check to make sure your frame is not cracked, mine was, that is why My belts were not working, had to replace entire frame, that is one bad item about husguavara mowers.Any one ever had problems with 48'' Husqvarna older model broke 3 deck belts with in 2hrs.has two new spindells .
Was used when i bought it so do not know the history ,was in need of carb & Manifold etc put more in than it was worth and still have issues.So there was no issues BEFORE you installed the new spindles?