If you have the removable strip in the headlining you should be able to access the centre part of the aileron cables. get a tensiometer and measure the tension. It should be around 30lbs. That's a ball park figure, you will have to compensate for temperature and adjust the turnbuckles accordingly. If it overly slack, you will have to check the pulley runs. Does it have an autopilot? The servo is on the right wing and there are extra cables from the servo to bell crank.
With regards to your radio interference, you should also be able to access the coax plugs to the VHF com antennas through the same access panel. Have a look, disconnect and squirt some contact cleaner. Failing that, it could be a bonding problem as mentioned earlier.