Hi, I am a new member looking for info on the transfer pump on my D4 7J1288 crawler.The pressure is very low and I am checking to see if these pumps can be rebuilt.I had it off and apart and it has had some work done to it before. There doesn't seem to be any gaskets between the layers so how does it seal? I used gas resistant sealant when I put it back together. I have a few other pumps off other D4's but the bolt hole patterns are smaller. Can I take a few apart and make one good one up? If so what worn parts do I look for? Also there is some sort of a valve in an additional part where supply line attaches to bottom of pump. What is this valve for? This valve doesn't look to be in very good shape.I think the parts book calls it a plunger. Any info is appreciated!