Get all the crud out of the old checkering that you can. It really dulls tools fast. Figure 75 years of dried finish and grit is like a fine sand paper on the tools. Dull tools will get away from you before you know it. Buy several checkering heads and do not be afraid to replace them. A few dollars is not a big deal when you get right down to it.
Do understand that if you redo the checkering you will know and see every mistake you make for as long as you own and shoot the gun. Humbles even the best job but that OK. As was pointed out before every job has a few mistakes which you will find when you do the job over again. Lets face it the person before you had a lot more experience than you do and he still made a few mistakes.
