My cleaning procedure - after the grate cools, lightly clean w/water and a non-scratch sponge (big crunchies, heavy build up), dry it thoroughly, brush lightly with oil before storing inside.
Now on to the meat of the issue, or should I say the heat of the issue -
@Bigdave all previous questions need to be addressed to see what the issue might be - meat quality, age, frozen vs. fresh, ingredients other than 80/20 ground beef all play a part. But the additional questions I have are as follows.
1) Are you letting the searing grate come up to temperature (very high heat) before putting the burgers on? This is important as it creates an immediate reaction with the meat once its placed on the grate and will allow the burger to be removed without issue. If the meat and the grate come up to temperature together there is always issues. That goes for other delicate meats like fish and meats with skin still on.
2) How long are you searing the burgers? Move too soon and you will have a the patties brake up - move too late you will have a blackened burger (or as I call them hockey pucks). This timing is all based on the thickness of your burger and temperature of the grill grate. I find that for thick half pound patties I stick to about ~3min a side.
The best part of this whole thing is you will have to grill more to find out what's going on - oh'darn... I vote that burgers stay on the menu until this whole thing gets sorted out - the family will understand. Happy researching!