Lioinel engine 2025

I have a 2025 that has not run in over 30 years. I notice that one of the two rotors that bring power to the engine does not touch the middle rail The spring seems to be disengaged so that it does not pop up. Is there an easy way to remedy this? thanks.

The roller arms are attached with clips which can be removed to get it apart. If the troublesome spring is there, not broken, and has not lost its temper, you should be able to make it like the other one. If not, you will need to buy a new spring.