well we are just trying to give you and idea of what to expect or look to be possibly wrong. I am not trying to give ammunition to attack the tech with by any means, usually if you approach a tech like that he will probably back off and may not want to give you the best service he could, most tech's don't like to be told how to do their job so i'm hoping you have a good approach in that matter.

we just give suggestions on the forum here to follow to help find the problems, most of the time we are on target and it helps quickly but sometimes it doesn't because some problems are not textbook type problems, or the descriptions we get can lead us down the wrong path, it happens :o/

And it all depends on the tech's experience and ability to diagnose the machine.

I'm sure if he has any experience in working on any machines like yours he should be able to find it.

But yes, you should expect to see him check the battery for starters, check amp draw and volt drop. If it is a lead acid battery he should check the water level and even specific gravity in each cell if he follows all procedures.
Once he rules out all those possibilities then he would move on to other possible problem areas related to the symptoms he sees.

But i just wouldn't stand over his shoulder if you know what i mean, give him a chance to prove himself. Then if he seems to be dragging it out and doesn't seem to be getting good results , I'd ask the service manager of his company to send someone else that has more experience because you are not satisfied with is work.
But i shouldn't really need to explain all this to you and it's really up to you to deal with that how you wish.
I'm just making suggestions and trying to direct you in a way that would help you know what it COULD be that is wrong.

I wish you luck on this and hopefully it will not take very long to fix.