My CX998 is also making the same noise in the rear of the device. I will be disassembling mine this weekend in an attempt to solve the problem and reply if I am successful.

As far as the wobbley handles and pedals, if you haven't tightened all the bolts recently and have used it regularly, they will loosen over time and the machine will become unstable/wobbley. If you did not assemble the machine yourself, I would suggest that you download the manual for model# NEL70950 (CX998) from the NordicTrack Customer Service website (link included) and use the exploded views at the back of the manual to know where to find the bolts to tighten. Using thread locker on the larger bolts will help keep things tight but regular maintenance includes tightening all fasteners and cleaning the ramps. FYI.

Good Luck!