I'd be afraid that would crack the 25yo fan if the clutch is good...
Naw, you don't 'jam' it in there. Just allow the magazine to 'tick' the edges and IF that breaks any fan blades then your fingers will do so too. Worst case scenario....you discover you need to replace the fan.
Fans DO get brittle over time and should be replaced when/if they don't feel flexible *when at rest* you can't twist them slightly by hand.
They are inexpensive to replace.
Borrowed picture below of a brittle fan that 'quit' and took out the radiator.