The list of stability tools listed above already indicates that many experimental parameters can be varied, and often, the road via mutations is not necessarily the easiest to arrive at higher stability. Some good old-fashion protein chemistry often can help a lot, but it also helps to run a gel of your protein after the essay that failed because of the protein instability. You would not be the first to stabilize a protein that was not unstable at all. If a protein does not express well, it is normally assumed that it is unstable. This is not true.
Instability is one of the many likely reasons for low or no production.
Also here, don't assume but determine. In this article we will discuss ways to stabilize a protein by mutagenesis. Stability can be defined in many different ways. A mutation that causes an increase in Tm is said to be a stabilizing mutation. It is also possible to use denaturing agents to determine stability.