Hi @paulbogosian
Check if the primer button bulb is OK and hasn't deteriorated or have a small crack in it etc.
If it is suspect, here's a [https://www.youtube.com/watch?v=z-jrsDkrKMo|video] that shows how to install it that may help.
Search online for [https://www.google.com/search?client=firefox-b-d&q=632047A|632047A] to find suppliers that suit you best. This is the part number for the primer button bulb used in the mower model that you selected in your question.