[campbdon]

I have already removed the sponge and reverted to original arrestor and it's housing. The modified version was indeed a homemade sheet metal enclosure in which the original arrestor+sponge+housing was nested. Now I'm back to discover what's actually preventing my engine from starting. I think I'll open a new thread under Troubleshooting for that.
Thank you all for your helpful suggestions. My engine environment is steadily improving.
DonC