After a (not so) brief hiatus, spent a short while working on my pair of 4800C's yesterday. I now have Tango's old one as well as the other. Two machines, two problems. Machine 1: when steaming, pump doesn't operate at all Machine2: group seal not sealing well. So this SHOULD let me troubleshoot and end up with two good machines relatively easily. First up is to fix machine1. I suspected the circuit board as switches and thermostats all tested OK. Swapped 'suspect' circuit board into machine2. Everything worked - pump pulses while steam switch engaged. Swapped board back to machine2 - no pump. Swapped out steam microswitch, even though it seemed OK - no change. Tested thermostats again, all seems well. Not sure what to check next. Will give it some thought, but any ideas are welcome. Oh yes, machine1 circuit board has date of 2001, machine2 has date 2004, but same connections on each.