Well, the R-10's have had their own share of problems which I will not deny, and I have encountered them even as a rider on certain occasions. There have been times especially during the late 1970's and 1980's, the consists could and can go out of service because of some slow or dead motors (especially in the lead car), door guard light indication malfunction and/or the power is not back up to full force even after the reset by the T/O. If there was any severe vandalism (i.e shattered glass windows) on the car encountered, it will be either *isolated* and/or taken out of service.
I did get an R-10 (#3218) one time that had some very sticky brakes on a 1975 southbound "A" trip towards 14th Street-8th Avenue, but the train just kept going eventually to the end of its run. Let us not forget that even after the 110 Westinghouse cars were GOH'd into as the green units, their ride on some them became so shaky and rough and a bit more noisy. You would think the trucks on some of the GOH green R-10's had permanent spotted wheels.
Yes, there will be times those R-10 units (but not all of them) will run properly without any severe problems on their "best" behavior, while there will be those units acting very tempermental and stubborn on occasions as well. In terms of the latter, this is probably one of the reasons in 1984 that NYC Transit took out of service and scrapped many troublesome R-10's at Coney Island Yard and Linden Yard, including the very first one built and delivered #2950 (ex-1803). Please do not get me wrong on this topic, but even though the R-10's are still my all-time favorite NYC Transit subway cars as a personal choice and preference, I am not going to say to anyone that they were always a problem-free fleet in their four decades of revenue service.
-William A. Padron
["Uptown to 207th St."]