Our princess range is 24 years old but still in good shape. One major gripe with the stove has always been the difficult control of the flame size. The control knobs rotate about 120° from low to high but the effective control span is only a few degrees in the middle of the rotation. It takes a surgeon's touch to modulate the flame. Does anyone have any experience in changing out the valves or doing a retrofit that will give us better control? Thanks.