Glad it worked for you.
As for a cork mat, the auction site has plenty of them, but you can also look at the double sided suede ones as well. I personally liked how they sounded over cork. I use both still but on different tables. The double sided suede is 1 mm thick and would be good on your Yamaha as it won't really affect VTA
Mine has the added perk of adjustable VTA
So the cork mat...
The one i left pressed at home is still curved. Not even slightly usable.
The one i cut at work, and then ironed, is flat. And warped. And it's about 1/2"dia too big now, so ironing the above mat is also not an option.
I'll try this again tomorrow...
step 1) iron
step 2) cut
step 3) see if there's a step #4.