Rick, I've taken 30+ Katos in repair that have Digitrax DCC boards and lose contact; It's that clip! Use an implement to hold the motor contact strips down, and solder them to the Digitrax board's contacts where that Kato grey clip used to go. That solves this issue essentially 100% of the time. The Digitrax board is thicker and its contact pads LOVE to oxidize, so the issue you're having is common to many Katos where the clip is still employed. The foam tape won't love the heat your decoder puts out anyway
I have 450+ Kato units that use the the mechanism or similar mechanisms that run flawlessly with soldering the motor leads to the decoder. The only issue I have had has been when the decoder failed, never on running even on large NTrak layouts. I solder the motor leads directly to the decoder on all locomotives.
