Weil EG-75 Boiler

I thank you all for taking the time to view and responding. On Saturday i performed boiler shut down and performed boiler drain and refill. Got a call monday stating no heat all day on Sunday. I figured i may have forgotten to turn emergency switch back on. Upon arrival and inspection pilot light was off . Relight , boiler kicked in. Did at one point hear a sizzling noise. Inspected maybe a drop on the pilot or 2 the whole time.  Was under the assumption maybe I filled it to much. After u running for about half hour i heard a hissing noise from under the vent area. Performed shut down, let cool for about half hour and resarted as I was trying to get heat to the building for the tenants. Past day  reinspected. No evidence of water around pilot area. Based on the pics provided am I ok or does it look like I may need a boiler replacement. Any thought on what may have occurred or maybe this was an exisiting problem that was present for awhile ? Thank you again