sjcprojects
Orange 🍊 Fan
Another not-too-intrusive option is to slip a bit of outer cable liner (or similar) over the shifter cable where it runs over the shifter barrel. This will effectively increase the barrel's diameter a bit, resulting in more cable pull.
It might give you just the extra bit of pull you need.
Thanks – I did think someone might have an idea for a work-around. I'll see if it does the trick.