Welcome to the thread.
I have a WBS 22E boiler, 10 years old. A similar problem happened to me. Namely, at start-up, the spark gives a flame for about 5 seconds, then goes out and error 133 pops up. The furnace tries to start several times until it finally gives up and only manually resetting the error causes another start-up attempt. In 2-3 times of manual reset, the boiler starts up. I bought an exchanger cleaning fluid, it was cleaned two years ago. I downloaded the maintenance manual and intend to do so in the coming days.
I have a question, is there a capacitor on my board that needs to be replaced? From the posts above mine, I can see that the board is different and the description of the capacitor on the board is also different. Second thing, should the electrodes also need to be replaced after such a period of operation (heating DHW)?