Lack of suction.
The first thing to check is that there is no blockage in the hose; sometimes you can pick up a large piece of paper or cloth which gets jammed in the hose, next if it's a bagless cleaner make sure all the filters (and anything that looks like a filter) are spotlessly clean. Blocked or dirty filters in bagless cleaners are you number one enemy.
If the hose is blocked remove it from the cleaner (the body end often unlocks, or is held in by two small lugs which can be pushed in with a small screwdriver, then just push a broom handle down the hose and push against the obstruction to dislodge it.
Brush not rotating.
This is caused by the belt breaking. The belt may just have been old, but sometimes if you have rugs on the floor, they can catch up in the brush and "lock" it putting strain on the belt causing it to burn out. More recent Panasonic cleaners have two belts with a pulley linking them; a small belt goes from the motor shaft to the small pulley, and a longer belt goes from the large pulley to the rotating brush (beater bar). To replace the long belt, undo the screws in the base unit, the just lift the brush out of the base and fit the new belt.
Important; never touch the rotary brush when the cleaner is switched on.
The cleaner overheats and cuts out.
Check and make sure the filters are all spotlessly clean. It's best to wash them out with warm soapy water, then leave them in the sun or on a radiator to dry out. Make sure the hoses are not blocked up, and if it's a cleaner with a bag, make sure it's not full.
If none of these cure the problem, the it's probably the motor at fault, which will need the attention of an engineer, unless you are happy doing your own electrical repairs. However, motors for Panasonic cleaners generally cost about £40-50.
Important; never put wet filters back into a cleaner to use it, you will ruin the motor.