I didn't have that pawl on my Widgeon (must have got lost long before I bought her) so I decided to check out the Spindrift/Rebel DS I manual that I found on-line........ guess what? No mention of that pawl or how to use it. I've added a couple of pics of the piece of the O'DAY lever assembly, if this looks anything like what is on your boat, you might get some help by calling Rudy at D&R Marine (508) 644-3001. He is an O'DAY Guru, and may have the advice you need. I still think that your best bet is to post a question on the Day sailer Class Association web site, you don't need to join to ask a question there (last time I checked?) I used to be a member of the DSA, but had to drop out after I lost my job and the dues were more than I could justify spending since I don't race. Anyway, there are a lot of DS I owners there and I'm positive that you will find at least one who owns a DS I of the same vintage and manufacturer as yours.
If it helps, here is how O'DAY described the operation of the CB.
"First push lever on centerboard trunk forward. Lift the catch at the lower forward corner of the handle and pull the handle back lowering the centerboard. Caution should be exercised always in lowering the centerboard. The catch pin can be broken, if abused. We recommend that you gently push the centerboard lever forward and then raise the catch." By "catch" they mean the pawl.