can you try to place it first in the other part off the case.

if you firstly put the lens through the upper case then offer the two parts together taking care to line the plastic lugs (marked red) outside of the soldered connections (marked yellow) it should fit tightly good luck

yes I have similiar problem that component under lens is very proud on pcb and will not let lower casing push up over pcb I propose filing a little off lower housing otherwise I will put too much pressure on pcb

are these original cases from the cam?

I just had the same issue with a cam case I printed, Put in lens half first, its a very tight fit, but it works..

original case yes ,it was so tight had to put quiet a lot of pressure to seperate housing problem now solved there are two vertical supports on lowering housing that support the pcb ,use a harp knife and trim both very little is necessary and it will remove the pressure on that component resting in front of pcb and allow you to re assemble quite easily Pat :P