First, just where the heck is the air filter? I looked at the air intake and it seems to go into the battery box.
This is the darndest system I've ever seen.
I'd like to check and then replace the air filter.
It's easiest to remove the battery cover first, next remove the air scoop (pretty simple), next lift up the air filter cover below and pull out the old filter. I replaced mine with a K&N filter (washable and lower profile). The new filter slides back in and seats like the old one. K&N filters having the lower profile are easier to put back in, good luck.