Three green gear down conversion?

[n86121]

Well,

If you DO have a green light, they are down and locked.

If you do NOT have the green light
then look left and right to the sides

If the gear legs are sticking out to the sides
they are down.
Maybe not fully locked, but not an issue for landing
They WILL stay in position.

So the only thing left is you MAY have a nose gear problem.
The best means to address being a wing mounted mirror so you can see underneath.