Just a couple of cents of opinion here. HE is my hobby on the farm. My "paying business" (at least it paid up until this recession) is selling horse equipment. On the logo- the advice not to change it was very good. You've spent years getting it recognized. No harm in a slight refresh, but keep the basics so that it is still recognizable. Remember when Coke refreshed their logo a few years ago? No you don't because it was very subtle, it just looked a little bit neater, but still was instantly recognizable.
On the toll-free number: be careful. I have about 25 of them we use to track advertising. But if I hadn't had them for 15 years I wouldn't now. The people who want to call you for business will. In this day of free cell calls, long distance charges aren't what they used to be. But it won't take much for you to have $200-400/month in calls. Just my thoughts.
I like the current logo but I do wonder about changing the "free quotes" part to something the sounds like a larger firm. If you want to look larger, maybe adding " Since 1974 (or whatever)", or Corporation, or some other legalese? Or adding to make "Earthmoving Contractor" .Here in the states you'll often see LLC or Inc. after the name to show the legal status. It does add some legitimacy. So sorry to ramble, but the psychology of business marketing can get so interesting & confusing.