I'm not sure. If any other models used that same separate manual oiler like that or not.
The check valves are in the two fittings that screw into the pump body and the inlet and output lines go to them.
Mr. Modified, I got a CS-452VL parts saw coming from Mark Heimann the first part of September. The IPL shows the same part numbers for the check balls and springs as the 900's. I will pass this saw along to you if you'd like as I'm only needing a couple parts from it.
Echo part numbers: 43701200330 Check ball and V450000290 Spring
Link here: http://www.arboristsite.com/chainsaw/241965-2.htm
je