John,
Defender Marine does carry the seal kit for the Survivor 35. Here is the link:
They also carry the membranes. Here is another tip: On Ebay you can find the manual version of the Survivor 35 intended for use in a liferaft. I got one brand new and unused for about $275 USD. The pump is identical to that of the power model. You only need to swap some bolts to mount it to the motor. I went down this path when a seal kit would not fix my unit. It is once again working great.
Please do note that the Survivor 35 which you and I have is different from the 40E unit.
Jeff Beller
S/V Journey
Sea of Cortez