Warm Start Boiler Summer Leak

Sounds like a leak at a mating surface; not enough gasket material or an imperfection in the cast iron.
I’d keep the temperature at 130F and cross your fingers.

is it leaking or is that condensation? doe it actually fire? if it fires only to 90 it is going to condense.

the rubber gaskets over time get used to the temp they are working at and as they age, they lose resiliency. You upped the temp, and it stopped leaking.

If you can get a new block under warranty that is a good deal. If you can continue to use the old block and get the new one that is a better deal. I doubt they want it back but they probably have some type of verification system but I would look into that.

Chances are at 130 you will run that block for quite a while

As mentioned above, tightening the connecting rods is a very good idea. Removing the section(s) can be a painstaking and laborious process. Especially if doing it alone. Raise the temperature first and leave it up. That should cure the leak.

what type of hear emitters do you have? Cast iron radiators of fintube baseboard?

You may need to bump the temperature up to more like 150 minimum. The temperature control has a differential, at 130 shutoff it may drop to 110 or lower before it fired, it may condense “sweat” at low temperatures

It should not run more than 10 minutes below 130 when the heat is on

A couple of observations.

The warranty for your year boiler does not seem to be pro rated. So anytime between now and 2034 should be fine to get new boiler under warranty. But I would not wait until then. You can keep the new block in storage until you thing the leak is beyond control.

The photo of the rest on the side of the block and the photo of the water under the boiler are sufficient for the warranty claim

After 2 years the old block need not be returned to the factory. From my experience, 'field scrap" is the normal warranty procedure after 3 years in service.

Still the upper port gasket leak qualifies as a leaking boiler and Weil McLain will usually honor that when it is brought to their attention via a warranty claim. The worst that can happen is the warranty folks at WM say no. Then you appeal and they say no again. But I remember when I did WM warranty claims, I could talk them into covering that exact situation. The warranty coverage uses the term "heat exchanger" not "boiler section" on the WGO, WTGO and SGO warranty form. See copy of warranty form here Weil McLain WTGO 20 Year Warranty

I would guess not. Since this is a WTGO boiler it was equipped with a tankless coil, that would mean to offer DHW priority the circulator would stop pumping cold radiator water when the aquastat reached the low limit circulator cut out temperature. The boiler would always maintain 140° or more if the low limit was set at 160° with a 20° diff. No need for boiler protection in this case.

Now that the cold start boiler is an option, they may need to think about boiler protection with a bypass of some sort, or some reverse strap on aquastat that keeps the circulator from operating when the supply temperature is below say 150°. the circulator would cycle several times as a result, but it did that when it was operating for DHW anyway. So no big deal.