When using the NIXY electric pump the gauge will move back and forth at a rapid speed as it inflates the item. The pump has two stages, the first stage quickly pumps the board to about 5 psi and sounds like a vacuum cleaner pumping air in. The second stage is much louder, and the pump will shake. Don’t be alarmed, this is normal. The second stage slowly pumps the board to the higher psi and will stop automatically at the psi that you indicate on the dial.