I have 3 PFM Passenger Cars with I believe original Truck and wheelsets.  They roll poorly and the brake assemblies hang low and occasionally short out on track.   All six trucks are similar although some are significantly worse none are what I would term good.   Is there a recommended process to tune them up.   While they look great, considering the range and consistency of problems, it would seem I might be better off simply replacing.   So besides the tune-up option, i am looking for replacement recommendations.  Thanks for any help!
Martin Wade
HMR Railway