If so, the best way to give them a thorough cleaning is in a self-cleaning oven, let them completely cool down then spray off with a hose outside.
We do that to our drip pans (blank & FlameZone), & grates about every six months. Just make sure you have good ventilation because it makes a LOT of smoke burning all the crud off.
I ran my flame zone covers, the flame zone itself and the racks through the dishwasher, and with the steam function. After a bit of scrubbing, it all came clean. I then wrapped the covers and the flame zone with foil.
I'm hoping for a much cleaner grill.