Really weird trouble with Pool Heater

Hey. New to the forum. I have a Jandy LX pool heater with some problems. It didn't start at the beginning of the season so I replaced the pressure switch and it started right up, but it won't stay running. It'll run enough to heat the temp a few degrees, but then just stops altogether. I tried adjusting the pressure switch and it doesn't seem to make a difference. I also am not really sure which wires go to which terminal on the pressure switch. I've tried both ways and the heater works the same either way. The weird thing is after it stops running I can get it to come back on by pulling or slightly banging on the control board on the top of the unit. I hear a click, the pressure switch light blinks once and the fan starts running. However, this doesn't always get the heater to ignite. The fan will run, I can see the ignitor glowing through the glass eye, but as soon as the gas releases the ignitor goes out before the unit fires and then the fan stops running. It doesn't cycle through 3 times like it's supposed to , it just shuts down, and I have to go mess with the control panel again. Once in a while it will catch the flame and run for a while, but won't stay running. Any ideas??? Thanks.