Nikkor 135mm JIS bayonet screw heads are damaged. How to remove?

[68degrees]

I have a 135mm AI MF Nikkor lens with the bayonet mount screw heads stripped out from apparently someone not using a JIS screwdriver. One of them will come out but the others are too badly damaged. Can you advise me how to get these screws out and where I can get some replacement screws. I have JIS screwdriver bits but the screws are too damaged. Any ideas? thanks

 

[E. von Hoegh]

Try setting the correct screwdriver in the mess and giving it a light tap. That might give enough grip to turn the screw out.
Otherwise you'll have to drill the heads off, turn the stumps out, and get new screws. Use a drill just slightly bigger than the threads.
Oh yeah, find whomever butchered the screws and punch them in the mouth for me

 

[MartinCrabtree]

Use the proper screwdriver. Clean the head of the screw (and screwdriver) out gently using a stiff bristle brush. Apply a little heat via a hair dryer. Then apply a little abrasive compound like lapping compound to the screw head and insert the driver pushing firmly while turning. That should do it. If lapping compound is a difficult find for you make a viscous paste of cooking oil and baking soda as a substitute. It gives the screwdriver additional "traction" and keeps it from slipping out so easily.

 

[shutterfinger]

Before trying the suggestion in post 3 put some acetone around the head of the screws. They may be set with thread locker which the acetone will dissolve once it soaks down to the threads where the thread locker has likely been applied. At least 1 screw will have thread locker.

 

[John Koehrer]

I've just drilled through the heads and when they're off & the mount's removed, taken a needle nose pliers and removed the screws. Once
the head and mount are gone, there's no pressure holding the screw in and the threaded section should simply unscrew. The exception is
when there's a sealant on the threads. That's frequently solved by heating the remaining part of the screw.