I was about to say that Voyager likely also suffers from the Pioneer anomaly, which is suspected to be caused by the RTG's thermal radiation pushing the craft off course [1]. But according to wikipedia we can't really tell because the effect of the maneuvering thrusters that keep Voyager aligned is much bigger than the Pioneer anomaly (Voyager 1 has fuel until about 2040).
1: https://en.wikipedia.org/wiki/Pioneer_anomaly