pop/snap tuner help

I picked up a beautiful Stromberg-Carlson 220 cabinet stereo for $15 at a yard sale.The cabinet is in very nice shape.I tore it apart and threw out the record player for starters.It has a 14-16" woofer in the center of the front behind fancy fabric.On each side behind thin doors are a mid and tweeter.The cabinet opens from the front.2 doors to hide the electronics.The tuner in it is a SR-445 and the 15wpc amp is a ASR 220B.Itn was all working fine on the bench with some bookself Sony's as speaker.Last night I turned it onand there was a pop/snap sound from within the tuner.Now quiet.?Resister ?cap.Please guide me.I've put alot of time into this project and want it for a possible 2CH "home theatre" with a 32" TV on top.
I would like to add,the snap/pop was a single incident.The sound was a combination of what a snap/pop would sound like together,a 'snop' maybe? :~)
All the tubes and lights in the tuner light up.
The indicator tube shows a FM signal when the dial is turned.Just no sound.
I imagine I need to get a voltage tester to get going.
I'd like some guidance how to use it and on what?
As I said,I've put lots of time in this project and its a stunning piece.
Thank you-
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