Um, from experience, if you want to do "dirt and squirt", be very very careful.
I have jammed a lens, using the dirt and squirt method, and I have made leaf shutters malfunction. The problem with "dirt and squirt" is that it washes out the lubricant, but can leave the dirt and the dirt, in tightly toleranced parts, can lead to jamming and seizure of the parts. e.g. if you try to "dirt and squirt" a Leitz Summarit, you may jam the focus helix, then forcing you to take it all apart.
And in shutters, e.g. the B setting, requires parts to slide to work. Wash out all the grease, and the parts don't slide any more. Even using oil won't resolve the issue; you need to find the sliding part and use the correct grease.
I do not advocate taking apart more than necessary, but I do recommend disassembling the correct parts, and lubricating with the correct materials, and putting it back together correctly.
If you are paying for a full tear-down, then you should get a full disassembly, rebuilt and correct lubrication.
But if you are paying for just a minor service to get some small aspect of the unit working, then, hopefully that is what the tech does, and hopefully it is done correctly.
Timmyjoe - "Dirt and squirt" Wonderful!