I am working on a 109 for my grandpa ,so I have to replace the chain brake assembly ,couple rubber mounts and bar .It is have problem with the carb. My dolmar dealer almost flat out told I was not physically able to rebuild it on my own . Saying without having the right gauges I could not do it . So how hard is it really you got any tips . He was trying to me to buy a new carb instead rebuilding it .