Bit different to jet, but the PT6's that I'm familiar with (purely from a pilot perspective), have had issues before with over-temp, or approaching limits, report to maintenance and they change out the' ITT trim stick'.
In very lay terms they explained it as applying a correction to the ITT gauges etc, to keep the pilots happy, but nothing (engine-wise) really changed.
Does the Garrett have anything similar?
I can't post the link but Google 'PT6 trim', and the top article from Kingair Magazine explains it in more detail.