I have an older grasshopper 614 and I'm losing my mind trying to figure out how to drain the hydro fluid.  Is there a plug some where that I'm missing?  And is there a filter on the older models because all I see is the two reservoirs on top.  Please help!
		
		
	 
Well, I hope you already found an answer, but on my 614: 
-I used a piece of plastic tubing attached to a syringe to suck out the old fluid. 
-I almost ruined the reservoirs before I realized they are screwed in with reverse threads. 
-remove the top plate of the hydro pump to access the filter (really pricey items, them). 
-syringed out the rest of the fluid. Don't recall finding a drain plug. 
Also, ever since I replace the fluid & filters, I've had a problem with the fluid overflowing the reservoirs when hot. I can only fill them up to the lower fill line or the fluid expands out of the cap and splatters all over, including onto the V-belt which makes it slip for a minute or 2 when running. 'Slip' means it moves slowly until the belt heats up and stops slipping. 
I didn't have that problem before the fluid change. And, yes, the caps are on pretty tight.