I've recently noticed some "rumbling" from my left front wheel (HPV Gecko fx 20) so I checked out the quick release wheel bolt and axle bolt. both are very tight. Holding the wheel with my hands 180 degree apart and I rock it. I figured out the movement is on the bolt where the steering rod connects to the wheel. The bolt that holds them is very tight, but very tight, but there is play there and it moves up and down on that bolt if I rock the wheel. Is that normal or should there be zero play? Both wheels demonstrate this issue. The left wheel tends to rumble or vibrate more noticeable when I ride, no issue wit the right wheel, and maybe I mostly hearing it against the fender. But when I hold the wheel as described it's the disc rotor which restricts the movement. I"m worried this is dangerous and, if so, don't know what needs to be replaced or fixed. My mechanic is not a recumbent mechanic, just a talented regular bike mechanic. Appreciate any help asap. thanks.