Inside my TS-440 & TS-930 are (former) foam pieces. They have disintigrated into a pile of dust in the bottoms of the rigs. I am more than sure that Kenwood does not have fresh stock off these. Can anyone tell me what type of foam it was and where it was used in each rig? Maybe even a supplier?
I have a TS440SAT, but have not disassembled it. I also have a TS940SAT, which is a larger, I believe slightly newer rig. This answer applied to the TS940SAT.
The TS940SAT and the TS440SAT have internal speakers. Foam is used in the speaker system in two ways.
The first is as the material which holds the speaker cone into the speaker frame. If this has degraded, as it will, the fix is to replace the speaker. I have purchased replacement speakers (usually called drivers, to differentiate them from finished cabinets, called speakers) from an online company: http://www.parts-express.com.
The second use of foam I've seen in the TS940SAT is as a gasket to seal a sub-compartment around the speaker. This prevents parts of the box from touching and buzzing as the speaker vibrates and also creates a sealed chamber around the speaker to improve bass response. If the foam gasket has degraded, I would suggest a soft foam about 1/8" thick. If you don't easily find that, you might try some soft felt, available either from a craft store, or online from http://www.mcmaster.com.
There may be other uses of foam I haven't seen in the radio. It is unlikely that foam is used as an active component (such as for RF shielding). Foam may be used to dampen the vibration between other sheet metal parts prone to buzzing from the audio.