Regarding parts from McMaster-Carr for the Monitor 441 heater, I have ordered the items that HayZee518 posted to service my heater.

Silica sheet goods 1/16" thick, size 40"X40" - 9362K16 - $21.50 now $33.82
Silica Fabric - A woven fabric - .026 thick, 36" wide - order by the foot 8799K3 $9.54/ft now $10.52/ft
Silica fabric - .090 thick, 39" wide, per foot, 8851K33 - $26.56/ft now $27.09/ft
BOROSILICATE GLASS - Viewing window material
1/8" thick, 2" X 1" - 8476K321 - $1.20 each – now $3.96 each

I probably should have read his post better, as it now appears I have 3 different materials which I can use for a burn mat….and no gasket material…which is what I need most.

Other folks mention using 9323K21 - Fiberglass Paper Ultra-High Temp Insulation roll - 10 Feet x 16” x 1/8” for their gaskets. Do I need to buy this as well, or could I cut the 9362K16 board into gaskets?

[FYI - 9362K16 is a Heat-Shielding Millboard Insulation with a 1360 degree F maximum temperature, 39” long x 39” wide x 1/16” thick. The dimensions of this item make it expensive to ship! ($70+ in my case!!!)]

My husband usually does the heater servicing, and he has reused the gaskets several times, so I know I will need new ones. This year he is very ill, so I’m getting a crash course in many home maintenance jobs. He rebuilt the burn chamber a year or two ago, so I'm hoping all I need to do is clean the heater and replace the gaskets.

I'm also looking for the pdf of the 441 gasket template.

Thanks so much!