The simplest answer is don’t!
Replacing the knobs and handles are fine for regular folk, but if you are attempting to open and repair parts on the inside of the housing…DON’T. Several of these have a very large spring, under a lot of tension, that requires some specialized tools to disassemble and reassemble.
If that spring is let out improperly, it could not only do person injury, it is possible to break part of the housing, bend the flanges or mess it up to where the head is almost useless.
On any of the Bogen 519 or Manfrotto 516, 519, 526 and HDV series video heads, the best thing is let a trained technician do the repair.
If you are having problems, or for a tune up or for repairs, send your name, address, daytime phone and email address along with your tripod to:
108 Garner Road
Spartanburg, SC 29303
Once we have it, we will evaluate it and contact you. Please send us your daytime phone so we can reach you during business hours.
Lastly, if we are repairing your Manfrotto Product; we are recycling all broken parts and scrap articles. Almost nothing goes into the trash if we can help it.