Hey, y'all!

 I just bought a used Lead 12 Combo (1987, I believe) which I am loving! but I'm experiencing an issue when listening through headphones which has me very confused.

If the 1/4" stereo TRS plug from the headphones (Shure SRH240) is fully inserted into the "H.P./Line Out" jack on the amp the internal speaker mutes but I only get audio from the right earphone. If I insert the plug only partway into the jack (to the first "detent") which seems to be a very popular suggestion online then I get sound from both left and right sides in the headphones but the internal speaker does not mute.

Any suggestions? And if it's an issue with the jack itself what kind of jack (Cliff? 6 prong? 4 prong? PCB or solder?) should I be looking for?

Any help MUCH appreciated, this is starting to make me crazy...thanks!

I have an Origin 20c Amplifier that I purchased new last year. It must have been old stock because it appears the manufacture date was 2018. I believe this unit has the faulty Jack wiring since the labels for the external speakers do not match the owners manual (2 8ohm jacks, without the line indicating 16ohm for both). My question is, will this unit work with a single Origin 212 cabinet, assuming I unplug the internal speaker, or do I need to get it repaired. If it will work, which of the speaker jack should I use, the one in the middle or the one furthest from the 16 ohm Jack

Sometimes it works, sometimes not.  I have to fiddle with the input cable.

How do I replace the input jack on my CODE50?  Does it simply unplug/plug into the PCB?

Where can I get the part and a diagram?

Thanks.

I tried the factory reset. It seems the only thing that did was wipe out my presets. It did absolutely nothing for the noise from the input jack. The noise is like 60 cycle hum on steroids. I've tried four different cables that were dead quiet when plugged into my other amps.