I've been doing these for years leaving the tubes in the set; a turkey baster
with a short tubing extension (4"-6") will slip into the hole where the
expansion chamber is attached. suck out as much fluid as possible, remove outer
and inner lenses, clean everthing up inside the chamber, reassemble and refill
chambers . I put a small piece of paper towel under the chamber opening while
draining and refilling to catch leaks. Fill until fluid just starts to run out
of hole, reinstall the overflow/expansion chamber, reassemble the screen , and
usually only need very minor recentering to converge. I do the whole thing in
about 90 mins, including time spent explaining to the kids.