When you change the filter each month, just replace the dirty one with a clean one, and take the dirty one with you to wash at your leisure.  

He said everything was working well although he couldn't tell how old the actual pump was. He

Getting into this business is hard and there's a reason that most who start wash out and quit.

I've had it for 3.5 years and the only thing I have done is pressure wash it twice and fix the AC once.

Wash Rinse and Repeat.

Hey I can wash clothes for my cousin for $20 instead of him paying $30 to use the laundry mat.    

For example, I had a tenant with them and they needed to bag all clothes, wash them all (heat from dryer kills them while cold doesn't) and move all furniture to center of room in order to spray along baseboards.

Appliances at per hour rate Window cleaning, tracks, at per window rate, A/C filter cleaning / wash it 10.00Bath tub at hourly rate Key replacement, lock replacement, mail box key, remote control.Glass and screen repair as per item Carpet Cleaning extra spot removal, cigarette burns, pet odor Sheetrock repair, nail holes starting at 15.00 per roomNicotine smoke or grease smoked walls, wall wash, kilz primer per room charge, extra for ceilings.Any furniture left per item, list couch 45.00, chair 25.00, mattress 25.00  plus labor to move.

Then legally they do not want to spend the money chasing them as it will be a wash or put them into the negative for return ( spend 3,000 in legal to recover 1,000 of the 2,000 you are owed).   

It also has an unfinished basement where the wash machine and dryer are located.