My R5M was empty. Last time I looked I thought it was fully charged. So a leak needs to be found unless the adult grandson has been shooting it without topping it off. My fill tank is empty and I was just going to do simple. The fill probe was not sealing so I was wanting to hand pump still. Tried changing the O-rings and it still wouldn't seal. Wondered if when completely empty it needed more pressure to start it sealing. I could crank up the Coltri. Just wondering about the whole business. Anyone with R5M experience? TIA and Be Well, Bandito.