Technical Oil pressure gauge issue

Hi brains trust, was wondering if anyone has had a similar issue to mine. Have an Autometer mechanical oil pressure gauge, quite a few years old now, 2 5/8 Sport Comp, always ran fine, all of a sudden sits at 50 Psi when car is off and doesn't go down. Pressure rises to 60-65 when operating, so that's good news, but when turned off, only goes to 50 and stays there, no slow bleed down or nothin. Anybody seen this before? Is it sender, gauge or heaven forbid something wrong in my oiling system. Oil is fresh, engine is 350SBC 671 Blown and Vertex OAC mag.

 

mechanical pressure gauges don't have a sender. But they do have a tube, to let the oil get to the gauge.

if you disconnect the tube at the gauge, does it drop to zero?

 

Also check for a bent needle [sticking to the face or gl***]

 

If it goes back down when you remove the line at the back of the gauge like Squirrel said, then the tube is plugged. Remove it and either replace it or blow it out with brake clean and compressed air.

 

Is the back of the gauge open in any way. Like missing the lamp? I had an Autometer oil gauge lock up due to sand blasting.