Welcome to the forum!
In order to find parts for your tractor it would be quite helpful if you would post the model and engine specs for us. I did find a starter soleniod on ebay, but I don't know if it's what you're looking for or not. As for the air filter, if you post the engine brand and model number it shouldn't be a problem finding on online somewhere.
Here is the soleniod that I found:
Westwood Gazelle Ride On Mower Starter Motor Solenoid | eBay
In order to find parts for your tractor it would be quite helpful if you would post the model and engine specs for us. I did find a starter soleniod on ebay, but I don't know if it's what you're looking for or not. As for the air filter, if you post the engine brand and model number it shouldn't be a problem finding on online somewhere.
Here is the soleniod that I found:
Westwood Gazelle Ride On Mower Starter Motor Solenoid | eBay