Part A is obviously the disabling problems with Part B being the corroboration. So now we are at step 4 and 5. If you were working at the exertional level of the proverbial monitor guard then you are in trouble if you cannot prove your PAIN prevents you sitting and standing for a 8 hour shift without having to lie down to reduce the pain. One not only cannot play the violin anymore, but have problems typing, tying shoe laces, buttoning a shirt, writing, etc. If this is one of your problems, stress it .
Many jobs require good bilateral manual dexterity.
You cannot put the bolts in the box and pass it to be next guy on the assembly, if you have significant problems with your hands. It becomes obvious that good medical reports are necessary to obtain disability benefits at any age or step of the process. If the answer is vague, or if the person is not seeing a doctor regularly, the interview is over. You will need to give Social Security the name and address of every doctor who has information on your disabling condition It is in your best interest to contact your doctors ahead of time and discuss what you are doing. Unsubstantiated opinions from your doctor won't do.