The winch is inherently dangerous, so double thin about everything that you are doing - keep others clear... Read the TM
That said....
I keep thinking that your line in bound on the drum, but you should be able to see that. The shear pin should be aluminum, but the holes get wobbled and the new pins don't last long! You can't have the pin shearing every time you turn around. There are lots of times that replacing a failed pin is outright dangerous, because of where you are. Some of us use soft steel or brass pins, (once, a phillips screw driver) and a good deal of caution and 40 something years of experience.
As a practical matter, when your using the winch by yourself, winding it in as you describe, and are getting close to the tail chain, allow about 10 feet from the end/with enough time to WALK back to the cab, get in, and shut the winch down. If you insist on doing up the last few feet, do a foot at a time from inside the cab/get out and inspect the progress, then get back in and do a little bit more, till your wound up. As said though, its best to keep tension on the line always, which makes for a nice re-wrap, and that is tough to do by yourself. When you have a helper winching, ALWAYS have the helper (the one on the ground), keep a hold of the line with a pull on it. If the line is wound in loose, then a hard pull on it will cause the line to pull/cut down into the wraps and booger the line in other spots. I have seen that to the point of having to tie the line off to a big tree, and back the truck up under power to pull the line off the drum. A safety tip is to boldly paint the "In/OUT" respectively on the dog clutch, so you or others are not confused.
Another tip which may seem trivial: Be absolutely certain that the winch is in the gear you think it is! Mostly here, I am refering to NEUTRAL! You may think that you are all done, but have left it in gear, like power-out. It can be messy! The trick about not winding all your line in, but wrapping the extra in a figure 8 around you bumper, is sound advice, especially if you are not done yet, and just have to move a little. Keep some leather gloves under the seat, for handling the line/look out for whiskers. Never let a$$-holes form in a loose line - if pulled tight, they can cause a kink that will never go away.
Good Luck