Old age Frozen or misaligned pulley
Things that might cause a pulley to wobble: The pulley is bent. The shaft the pulley is on is bent. The pulley is mounted crooked.
Husqvarna makes Husqvarna
Bad bearings, abuse, just plain bad luck, improper maintenance and/or service.
its loose tighten the pulley
If you pry up on the pulley with a bar on each side of it and while keeping pressure on the pulley, hit the end of the shaft that the pulley is on with a brass mallet, the pulley will usually break free.
it is time to change bearing on that pulley
Husqvarna IF ended in 1971.
AYP Makes Husqvarna and Craftsman tractors
No, Husqvarna is owned by the Husqvarna Group. Electrolux acquired Husqvarna in 1978 and the company was spun off by Electrolux in 2006.
Age or damage from a failed pulley.
It will eventually wear out and break.