So you are trying to true a tubular wheel with a tire glued? Cheap tubs often are a bit wonky. They also get wonky with age as they dry out. If the wheel was stored resting on the tire, de-flated, it could have put a flat spot in the tire as well. The trueness of the tire is also reliant on the gluing job...if it is done haphazardly the tire doesn't sit straight. It is hard to do a good job of radial trueness (roundness) with a tire mounted. If the hop is at the valve, the rim valve hole prolly needs to be recessed...a metal countersink bit is best for this.