There is an ongoing discussion with a TurboTax user in a similar situation that might provide you with relevant information:
https://ttlc.intuit.com/community/retirement/discussion/re-excess-traditional-ira-contribution-in-20...
I interpret your reply as indicating that you received a 2014 Form 1099-R in early 2015 which you expected to have code J8 but instead had code J. It's unlikely that you'll get the broker to make any correction to the Form 1099-R at this late date.
I'm not sure how to resolve this. Did you report the regular distribution on Form 8606 Part III? If so, it appears that you still have an excess in the account on which you probably owe a penalty for each year 2015 through 2018 if you did not file Form 5329 for those years. (If you did not file a Form 5329 showing that you have no excess contribution, to start the statute of limitations clock for assessing the excess-contribution penalty each year never started running since Form 5329 is treated as a separate tax return for this purpose). Certainly you can treat the excess as still present in the account and make a regular distribution of the excess (without regard for any earnings) to be sure that the excess is eliminated, but not sure that that is necessary. I don't think that a conversation on this forum is the way to sort out all of the intricacies, so it might be best to seek local advice from a professional familiar with this sort of situation. (If this was caught earlier, before the statute of limitations on the 2014 tax return expired, the situation would probably be easier to resolve.)
