Your catapult issue - be aware that the catapult ramps on original MMs (don't know about MMR) had a manufacturing defect that worsens over time due to wear. There was an old RGP thread on this back in 1998 with Brian Eddy to identify the problem. From the factory the catapult wireform has a downward curve at the point where the ball starts up the rails, and that needs to be adjusted to have more of an upwards curve to allow the ball more speed up the rails. Over time the issue (ball not reliably launching far enough up the wireform to make it all the way around, and/or difficulty in clearing 2 balls in the catapult) becomes worse as a wear spot develops in the wireform at the point of that downward curve (so not a smooth path). The suggested solution was to insert a 1" diameter piece of wooden dowel (about 3" long) thru the sides of the rails at the point of the downward curve, and using the dowel as a fulcrum point bend the top two rails upwards. This modification allows the ball to pass more smoothly out of the catapult and along the rails, which helps in 2 ways: 1) A single ball launches more reliably out of the catapult, and 2) when multiple balls are in the catapult then it is easier for the first ball to be cleared which then allows the second ball to clear.
Making that adjustment certainly helped on my MM. I remember that when I did it years ago some significant force had to be exerted on the dowel to get the upper rails to gently bend upwards. I didn't feel comfortable doing that with the wireform ramp installed, so I removed the ramp to make the adjustment. I then used a couple of saw horses placed close together, a dowel long enough to rest on both saw horses while passed thru the wireform ramp, and I then exerted pressure on the wireform ramp directly by pushing down on it against the dowel while gently rocking the ramp back and forth (the dowel moves/rolls) to spread out the pressure on the ramp a bit. Sounds more difficult to do than it actually was.