Problem with Renault Fuego changes

Good afternoon fellow mechanics and enthusiasts. I'm currently experiencing a curious problem with my 1987 Renault Fuego. The issue is that when the engine is hot and after driving for a while, it's difficult to shift gears. Oddly enough, this doesn't happen, for example, in the mornings when I first leave the car and the engine is cold. I initially thought it might be low on transmission fluid, but it was only about a quarter liter low, and considering the clutch disc is only two months old... I'd appreciate any suggestions or similar experiences you might have. I WOULD REALLY APPRECIATE IT IF YOU COULD CLEAR UP THE MATTER BEFORE YOU TAKE THE CAR APART

Good afternoon, please give us more information: mileage, year, engine, type of use, usual driving style, type of oil and transmission fluid. This information will help us understand the situation; even the climate is a factor to consider

Friend. Based on the symptom you're describing, a locking mechanism in the box has shifted. When the box heats up, the metals inside expand, causing the effect you're describing.
I recommend you perform several tests to make sure it's really a gearbox problem and not clutch fatigue, as the symptoms are very similar.
Pay special attention to the engine's idle speed when it is hot and under no dynamic load, because if the engine tends to stall, the problem is even bigger and may be due to a failure in the axial bearing.
For any questions or inquiries, please feel free to contact me via email