Looks like & easy fix, but begs the question why is is broke.
If its an open frame type supply then maybe just got knocked while laying around or could have been cracked during manufacture. Is there any evidence the broken disk has been hot.
Of all the SwitchMode supplies that I have repaired, 70% of parts I get from old boards & no comebacks. These used parts are "burned in" during use & are quite reliable generally. (except output electrolytics that are usually poor quality or overstressed)
So look around for an old TV or PC power supply of similar power Watts & you get your part for less than free.