I think I would  try to blow it out with a air compressor if that doesn’t work a very small wire or jeweler’s screwdriver with using air at the same time. What do you think is in there? After its cleaned you can use WD40 lubricant sounds like you’re making good progress 

Make sure you don't throw away the cage inside the air filter if there is one!

New filter elements are available from Yamaha but generally do not include the cage.

Yep...keeping the cage for the air filter. 

Crisis averted on the ignition. Something sticky was in there...don't know what. I was able to get it out. Key goes in fine now!

Definite newbie question...if we wanted to test the battery is connected correctly, I assume we could switch to 'on' and flip the lights on real quick?  

 

Whoa. If you connect the battery backwards you might fry something whether the key is on or not.

Negative side of battery goes to frame ground. Positive connects to red wire. Post pictures if you're not clear on this.

Probably a poor choice of words on my part  . I’m confident the battery is connected correctly. Just thought my daughter would like to see the lights come on. However, I didn’t want to turn them on if it’s not a good idea given we’re not at a point to start the engine.

If everything is hooked up you can check horn, taillight your headlight won’t come on until it’s started 

On the generator models, the headlight should come on without engine running...  at least I'm pretty sure everything is run off the 12v battery.

(Magneto models need engine running for headlight)

You won't hurt anything turning on the key and headlight switch. 

OOPS my mistake MarkT is correct  on the headlight 

10-4 on the WD

The tank's been soaking in Evapo-Rust since Sunday afternoon. We're planning to empty and rinse it out later today, followed by hitting with a blow dryer on low heat. We're planning to follow the advice here, and add some oil to coat it until we can get it installed and full of gas. Question...can we just use 10W30 (was going to use this for the air filter) or should we use 2-stroke (like the Yamalube I purchased) ?