Hello, I have a Grotrian-Steinweg upright and was trying to find some info on its value for my Mom, Its a Grotrian-Steinweg,it has a unique shape for an upright and I haven't been able to find much, if anything on it.. it has a full-size, U-shaped, cast-iron frame. and radial-braced back construction. Model # 110, I believe it was manufactured sometime btw. 1950-1960, according to the serial number. If anyone could tell me anything I would greatly appreciate it, thanks?