Additionally, the gas channels need to be cleaned out as well. they accumulated debris and must it must be removed. a combination of q-tips, pampers baby wipes (use a chopstick to get in the nooks) and an air compressor are the tools of the trade.
The connectors and screws come apart pretty easily, just take a few pics as you take it apart, so you remember how it goes back together.
I would plan on doing this cleaning once a year to keep it running in top condition. It runs so much smoother you can barely hear it when it runs. We have an external intake on our heater to get the most fresh air to the unit as possible - a 4" foam intake filter is recommended to keep the grime out. There are some ATV ones that are available online that fit with a hose clamp.