8-month résumé gap, advice? after 15 years as a mechanic

I have been out of work for 8 months and worry about the gap. Thank you in advance. I am not sure how much to explain. How did you handle it on your résumé?

I listed the volunteering and course under the same dates and kept the explanation to a sentence in the cover letter.

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.