0041 Trouble with Dapol N gauge HSTs

For years I've had trouble with Dapol N gauge HST dummy power cars not being free-rolling - I show the problem and explain how Dapol handled it when I reported it to them. After a long wait I've received my HST Castle set, so was interested to see if that also has the dummy car issue. In the video I said the Castle set doesn't look like it's going anywhere near a scale 125 Mph at full speed, and that I won't be measuring it. After receiving a comment about that I decided to do a simple measurement and it came out at a scale 121 Mph! So actually it's scale top speed is pretty much spot on. My video about fitting a DCC decoder to a Dapol HST:    • 0023 Fitting a DCC decoder to Dapol N gaug...   I've used Dapol Imperium 2 Next18 decoders in all of my Next18 locos. The Polyimide (AKA Kapton) tape I used to insulate decoders: https://thepihut.com/products/polyimi... Other videos or channels I know have had similar dummy power car drag issues: Chandwell August 2020 update with draggy HST:    • Dapol HST a brief new arrival at Chandwell...   Kingswear N-Gauge episode 2 with draggy HST:    • Ep:2 Kingswear   Will's N Gauge Trains:    / @willsngaugetrains