What is wrong with it?
Check the primary winding with an ohm meter. If it is open, then I would suspect a small thermal fuse hidden under the yellow tape wrapping has failed. Those thermal fuses often fail from just "wear and tear" after several years, especially if there have been some power bumps over that time.
If primary is good, then it may be something else besides the transformer. Check the secondary voltages. If they are about right voltages, then there could be something wrong with the diodes to the right or the U3 device.
If primary is good but you have no secondary voltages, then you are more in trouble, as a replacement transformer will be difficult to find. Not impossible, just difficult or not worth the effort to repair...
Good luck.