I clean my Mars validators every 90 days or so. I use 1” paint brush to dust off the insides after I remove the bill transport or use an air to blow them out. I use a “Wet towel window wipe” to clean off all the dirt that collects on the white wheels and wipe off the upper and lower windows on the LED housings, then dry everything with a soft cloth. If the LED housings are damaged or scratched that will greatly affect the acceptance rate. A reject rate of 10 – 20% is unacceptable. Yes the acceptance should increase if you get a good rebuild. I’ve seen some pretty shoddy rebuilds over the years. My Mars supplier has been getting a few new AE2602 validators from time to time, he called me today said he got in 4 today.