Oil pressure

I have a 1976 kz400 and it’s a work in progress but the one thing I haven’t been able to do is get the oil light to shut off. I’ve swapped out the filter and put in new oil. I’m not sure what more it could be. This is my first motorcycle so I’m learning as I go, thanks.

Does the light go off if you pull the wire off of the oil pressure sensor/switch?
You may have a stuck switch or the wire is grounded out.
You can buy a cheap mechanical oil pressure gauge and put it in place of your oil pressure switch.
This will tell you your oil pressure. This is the US version of what you would be looking for.

www.autozone.com/gauges-and-gauge-access...ge-1-each/256003_0_0

Can it be a idea to connect a manometer and take reading on the oil pressure?

You will then know if its failure on pressure detection or pressure low...?