You should have a couple of drill bits in your kit. Stick to the small sizes first. There are two holes drilled in the accumulator body. You only drill those hole if there is no slot in that location. ;tu
Feed bolts are a one time use bolt. They must be tossed during a rebuild. If there is a lot of wear on the center support it will continue to move even with new feed bolts torqued to spec. You can see this when looking at the center support lugs. The fix is to machine the center...
The converter is shot. If you keep driving the truck the tranny will be shot too.
There is no way to clean all the debris out of the tranny when a converter fails.
Now to the original problem. The locking and unlocking of the converter was most likely a failing transmission range...