Is it possible to "fix" the rear gunsight periscope? Two fixed MG 151 20mm cannon in rear fuselage, firing to the rear and sighted by periscope
If by "fix" you mean "remove the MG151/20 cannons", I sure hope so.
The rear-sight periscope was never used in combat. It should be deleted along with the 'gamey as pig snot' rear cannon.