Technics AM/FM Receiver Model No. SA-...

Technics AM/FM Receiver Model No. SA-R377 has a small standby transformer and it is cycling on and off. I used a hair dryer to heat it up, and it comes on. As it cools, it won't work anymore. This is true even with an ohm meter ant the transformer is removed. The ohms value change as it is heated and cooled, enventually it opens and has an infinity reading on the ohm meter. I tried another standby transformer from my junk pile, and it worked perfectly, but now I can't turn it on and off with the with the button in front of the receiver. I am forced to used the remote. Wierd, can't solve this problem with the standby transformer I installed. By the way, I just chose any bystand transformer, I din't use exact replacement because I could not track down the OEM part. Thanks to any technician who can solve this.