Is one permitted to lean on the Tebah?
The Tebah in the Bet Kinesset is categorized as "Tashmisheh Qedousha" (an item which services a holy article). The Gemara in Masechet Megilah teaches us the difference between "Tashmishe Qedousha" and "Tashmishe Misvah." Tashmishe Qedousha are those items service holy items written on parchment, like a Sefer Torah case, teffilin case, the ark (where the Torah is housed), or the tebah. When any Tashmishe Qedousha become unusable, they must be placed in Geniza and cannot be thrown away. However, Tashmishe Misvah, which are items that are used for performing misvot (ie. a sukah, lulav, shofar, sisit) may be thrown away because there is no inherent holiness in the item.
One may not lower Tashmishe Qedousha to a use or function less holy than that
they are currently being used. Therefore, a Tebah which the Sefer Torah is placed
on, cannot be used for a hazan or Baal Qoreh (Torah reader) to lean on. However,
if there is a parochet a cloth covering) always on the Tebah, the tebah is a "Tashmishe
Tashmishe Qedousha" servicing the item that services the holy body, while the cloth
is a direct Tashmishe Qedousha. Here one may use the Tebah for non-holy purposes
and throw it away when is becomes unusable.