Unit comes up with check engine light on after several hours of service. Always code 77. Changed out sensor due to wiring rubbed thru. Was good for 3 days. Code 77. Output voltage stays constant , no pulse up and down. I'm assuming that this is a rich signal. Machine has 4435 hours. Was wondering if lp vaporizer is full and needs to be replaced. Is there. Kit available or full replacement ? Will this take care of the rich syndrome or is it best just to hook up the laptop?

Model is a G33P-5 GM 2400 engine. With Woodward lp system