I can think of a number of good reasons why you may not want to do this yourself even though you know how to it. So, your decision to call a licensed electrician makes sense to me. Since it is a rental property, it makes sense to me to use extra caution and use a licensed electrician. It is better from a liability standpoint; it clarifies for the tenant that you used a qualified professional to look at, diagnose, and fix whatever the problem is; the cost is a deductible business expense; etc.
In thinking more about your original post, it occurred to me that there may be another reason why 1 or 2 of the breakers (or more) are having a problem. For example, if one of the breakers had a loose connection in the panel, it could cause arcing and heat that in turn can cause the contact in the panel (is it called the bus bar?) to actually melt. If that is going on, an electrician will see that problem and be able to tell you what your options are in terms of safely fixing the problem. I think in that scenario it may be possible for an electrician to move the breakers to a new position in the panel and cover up the old breaker slots, or maybe a whole new panel will be needed -- or some solution in between those two options.