Plug for Trim Reservoir fill

[Carl]

When I removed the plug last weekend to check / add fluid to the T/T reservoir, the plug seemed really dried out and the slot and hex are now in such bad shape I need a new plug. This is a part that is no longer available from merc or many other places. I found a place online that had stated they had one, but today I get an email from them stating they don't. I am frustrated because almost a week has gone by which I could have been searching for another source. I have also been searching ebay.

Does anyone have any other ideas or a parts motor that might have this part that they are willing to sell?

My motor

Mariner 150 HP

Serial = 7150726
Model = 0A906046

The mercury part number for the plug assembly (plug and oring)
= 99609A1

Thanks