That's your best bet. And
DO NOT replace with a 20 amp receptacle if this is not a 20 amp circuit. Remember what I said about configurations being designed for use? Well a 20 amp plug can plug in to a 20 amp receptacle. If these are on a 15 amp ckt than you can potentially overdraw the circuit. It's different the other way around. You can have multiple 15 amp receps on a 20 amp circuit. No individual recep has the capability (under normal circumstances) to overdraw the circuit. But even one 20 amp on a 15 amp circuit can potentially overdraw due to different design limitations of specific configuration.
Most likely causes, in order:
- Worn receptacle.
- Backstabbed receptacle, or multiple wires not pigtailed.
- Worn or poorly manufactured cord.
- Bad capacitor.
Obviously ignitor is functioning if lamp is starting. You can have a bad capacitor and still function depending on ballast design. Just functions at a lower voltage. Or you can have a bad cap that will make the ballast draw 2x the current. Most ballasts have a power factor of .50 before before a cap is added. And .90 after cap. The reciprocal of .50 is 2. So with a bad cap, multiply current by 2. With a good cap, multiply by 1.1 (reciprocal of .90) That's why a 1000W ballast will draw around 1100 watts.