You can try screwing in the OPV all the way (so it cannot bypass any water), You should see about 13 to 15 bar steady pressure against a blind filter, if the pump is fine. If the pressure drops and rises (with the OPV defeated), the pump is dying. If the pressure is fine, the valve seat and spring in the OPV need to be cleaned.

I know were the valve is but I don't know how o adjust it it does not have a screw likes the ones Ive seen on the videos

A non-adjustable OPV would be new to me. Does it have a hose going to the drip tray or back to the tank? If not, it isn't the OPV. If there is a hose, and no adjustment, it is a safety valve, not a regulator. If that is the case, you will see no water coming from it when you run the pump against a blind filter. If you see water going into the drip tray or back to the tank; but no adjustment screw or collar; I have no idea what is going on.

The OPV on the Brasilia is similar to the Anita and Andreja. Turn the adjustment nut to the right til it the OPV closes (though I have not done it before). See:

Andreja Premium & Anita: Adjust brew pressure

I changed the pump . it does not oscillate any more ,but It feels weird. Does the brew pressure need to be re adjusted for the new Pump?

You may want to check: the OPV spring doesn't change, but the pump curve does, so it could be that the way the pressure responds to as the OPV opens will be different. It's standard procedure to check pressure every 3 months or so, and certainly when changing the pump