Having installed numerous PMM systems in both grand and upright pianos, I find that it is much simpler to install the system in the grand piano than in the upright...The caveat being that there is a dirth of room inside an upright case...This makes the installation process an adventure in engineering at times...One of the primary problems are the support "horns" that extend from the plate under the keybed...These are usually in the way when you are attempting to install the rail system, and they have to be refigured in such a way to still perform the function they are intended for, and yet allow the rail system to be installed...One can install the rail in the front of the horns, but that moves the position of the rail solenoids forward on the keys, and, in many cases, this causes the entire key to lift up horizontally, instead of just rocking the tail of the key up and operating the hammer abstract. Good and proper installations are possible on uprights, but one must do his homework first...Best wishes, and good luck...
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