platform bolt sealing?

'89 Saltare. Tightened rudder packing today as I had some water intrusion keeping it in the water. Cured that leak which was a tricle. I see a trickle from what looks like the top center platform bolt. There is a thresed plate attached inside the transom for each platform bolt that is visible. Outside there are no bolt heads as I expected, I'm guessing I need to pull the platform off to get access to the bolts?

I hoped to tighten and slow the leak now while on vacation and boat is in the water. Now I'm thinking wait abd reseal with 5200 after vacation. Bilge runs about once an hour... Not thrilled with that but at least it's a new pump and wiring.