I’ve learned this the hard way before……if your new set up on the tender axle has too close a spacing, when the axle turns it acts like one continuous ground, and you’ll get no chuff. Chuff in is looking for that nice clean break between open and closed to chassis ground. OTOH, I’ve had cherry switches go bad, and keep a closed ground….with the same result, no chuff,……I’d agree with Norm, and fix the cherry switch issue you’re having,….
Pat