Hi,
I have not seen the modified arm, but in theory any stepper motor driven mechanisms can "slip", i.e. not move physically when a pulse is applied.
This is only really an issue when no additional position sensor is fitted.(The software controls the position of the arm by applying a known number of voltage "steps".)
A good example of the calibration procedure is on some modern speedos where the clocks travel to max as switch on, then return to zero. Looks very nice, but this is actually the stepper motor calibrating itself by overdriving the needle, in the same way that the swirl arm is calibrated.
My fix just uses a physical stop to hold the mechanism when being overdriven, rather than letting the arm take the strain. Provided the stop makes contact JUST before the mechanism runs out of travel, it is a perfectly good fix and will save the arm taking any more excessive stress, which causes it to break, in time.
For this reason, I would think that, even with a new arm, the software would still require routine re-calibration.
The issue seems to be that the motor is VERY (possibly too) powerful and, as I found, when you strengthen one part, it was a matter of time before the next weakest part in the mechanism broke! I was concerned that, in the end, I would have to strip part of the engine down to repair internal parts of the linkage. The idea behind the bump stop is to eliminate stress in the setup, and to date, this has worked well.(You could always combine a better linkage with the bump stop, if you want).
Hope this helps!
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