Heater Core Cover?

[Just a Six?]

So Ray & I have been following Steve's instructions on vortexbuickset c.com & it was going way too smoothly until the gremlins showed up. I can lift up the cover of the case 1"-2" all around the front, middle & sides easily but right in the centre against the firewall it won't budge? Not Up, Down, Left or Right? Looking over the pics & instructions we did Not remove the 4x 12mm nuts & 2 brackets for washer trim support. I don't see how they would stop it but something is blocking it? Any ideas?    

[Just a Six?]

I went back at it & success it's off! The issue was the weather stripping just holding hard back & centre. Now I looked at the heater core & I'm not sure it is the problem? I blew some air in & put my finger on the other tube & it seems pretty tight so maybe its not the problem? I have a new one on the way so it's going in but I'm now in need of a line on Weather Stripping for firewall.
Also which Sealer I can use? Black RTV? Right Stuff would be impossible to open in the future. Thanks

[ULYCYC]

Under the air intake screen there are more screws.  Don't remember if its 2 or 3

[Just a Six?]

Thanks Ed I originally did miss one of them but it was sealed so well from the factory we were both pulling on it to finally get the thing out. They did a good job of sealing it.   

[1KWIKSIX]

Suggest you use 3m butyl tape David

https://www.amazon.ca/Butyl-Window-Ribbon-Sealer-adhesive/dp/B073SFP21D

[1KWIKSIX]

RMI-25 is good stuff, however will find any weakness in your cooling system .
i suspect you’re Heater core was marginal and the application of RMI-25 did its job and found some problem areas and now it’s leaking. I’ve heard it doing the same on radiators too if their not in tip top shape 

[Just a Six?]

RMI-25 is good stuff, however will find any weakness in your cooling system .
i suspect you’re Heater core was marginal and the application of RMI-25 did its job and found some problem areas and now it’s leaking. I’ve heard it doing the same on radiators too if their not in tip top shape

Thanks Dave now I know what to look fo.r I've used the RMI 25 for years but I flushed it twice before the new rad went in & maybe it exposed the leak a little more.

[Just a Six?]

This stuff is what the factory used to use or very similar to it. ordering some up later today.
3M 8578 Strip Caulk, (3M-SCB)
When I put up the link I get Access denied I have an Amazon link but it shows my info but it looks like good stuff.

[Just a Six?]

Ok so made some progress with the heater box cover it's all cleaned up & I'm now looking for the Long Foam 2" wide strip with the 4 holes that goes on the firewall so if anyone has any idea where to find one it would be Greatly Appreciated. 

Also I have the Spectra Heater Core & it has some foam strips on the side but it's still a bit on the small side. Thinking I have some old intercooler & MAF rubber connectors so maybe I'll cut those up if I don't find an alternate solution? Any other ideas?