Yesterday I removed the handle-spring-piston assembly from my Microcasa a Leva and then removed the dispersion screen. I carefully cleaned the handle spring piston assembly and used my usual bicycle chain lubricant to lubricate the pins and roller. I carefully cleaned the dispersion screen and seal and set them aside. I now ran my usual wad of paper towels down the bore. I inspected the bore, and it was perfect. I cleaned the bottom of the bore a bit, and then I ran a second wadded towel down the bore and it was time to reassemble.

I now carefully used the standard Dow 111 lubricant to apply a coating to the seals on the piston. I made sure that there was no visible deposit of lubricant below the seals. I now very carefully put the handle-spring-piston into the bore, taking great care not to damage the seals as they entered the bore. Now comes the special part: Just after the top of piston was just completely inside the bore I put more silicone lubricant just over the lip of the cylinder bore. The "piece" of lubricant was about the size of a lima bean, and I spread it all the way around the inside of the lip. I made sure that all the lubricant that had gotten on top of the group was pushed back into the bore. I realised some time ago that the TOP of the MCAL piston should have plenty of lubricant. Now I pushed the assembly all the way into the group and put the two tapered Allen screws in place. I put the seal around the dispersion screen, dropped it into the portafilter, and pushed it into place, and "locked down" the portafilter. I removed the portafilter and the dispersion screen and seal were in place, and the service was complete.

The top of the MCAL piston runs dry and open to the atmosphere. Brew water never touches it or the spring. I have noticed on previous servicings that the upper part of the piston walls remain smooth and perfect when a bit of excess lubricant is added as described above. Otherwise it get stained and even a bit rough. Other machines like the Cremina and the Pavoni levers have boiler water on top of the piston. One does not want excess lubricant on top with these. I have found that putting a bit of extra lubricant on top of MCAL pistons can extend the period between servicings.