Yeah, I've had small leaks coming out of the top of the group twice. Lubing fixed the problem both times. If it doesn't, there is a seal replacement kit.
It's a real easy job, just remove the four hex screws at the top of the grroup and carefully pull out the piston. There's enough play in the wire to the microswitch to lay the piston down on top of the machine. When you put it back together, the conduit tube for the microswitch wire may need to be jiggled back into position. There's several silicone NSF certified food grade lubricants you can use. I use Novagard G662, simply because that's what 1st Line sells for the machine.