I have torn apart and replaced the O-rings on my push rods twice before. (It's a 1999 model). The plastic spacer was destroyed both times. My question is does the spacer go to the front or the rear of the o-ring or is there one in front of and behind it? Also when replacing hydralic fluid, are there any tricks to keep air out and do a better job of it so I don't have to tear entire unit apart for a third time. I have taken everything apart and cleaned it both times in the past.