[Mondial]

I have no experience with that model, so I really can't be of too much help. The radio has a ratio detector which combines the functions of a limiter and discriminator in one. You might try connecting the scope to the junction of C312 and C313 which would be the detector output. Connect the generator as per the alignment instructions and see if you can get a classic sideways "S" curve with a sweep input. You want the center portion to be symmetrical and as straight as possible.

As a help, you might try to find sweep alignment instructions for another radio which used a ratio detector and see if it can be applied to your set.