If there's too much coffee in the flask, it's stricter. It always worked harder with mine too. As far as I know, holding the machine firmly against the point is normal. The machine is too light and is not fixed. It is the same with the current piston machine of the same size. It is important to use the corresponding dosing spoon and always press well into the piston.

Do not put too much coffee in the filter holder and pack it down well to make it easier to insert the filter holder.

This is probably a mistake, I don't have to hold the machine to insert the portafilter.