I have gone to 3 different places in the last year for service on 2 sewing machines. I took the first machine to my favorite Sew Vac in CA, I took the second machine to a repair shop in AZ and to a Sew Vac type shop in WA. The average price was $90-100. So I think $179 is way too much.
It's really easy to check the timing yourself on a machine, I've done it a couple of times and both times there was nothing wrong. But it is kind of a pain to adjust it if it's off. Here's a visual tutorial.
http://www.sewitworks.com/timing/
Check all the obvious stuff first. Most of the time it's something simple. The machine needs a good cleaning, oil in the bobbin race, a needle replaced, removal of thread that shredded, broke and jammed up inside the machine, bobbin tension needs to be adjusted.
Look at your spool of thread. If it doesn't look like it is wound smoothly on the bobbin, toss it. Pull the thread out about 8 inches. Is it relatively straight and smooth looking? That's good. Does it curl around and around and look really wavy? That's not good. It was not wound correctly and will wreck havoc with your machine. Toss it.
You say your top thread gets tight. Check your thread spool. If you use Coats and Clark thread, the new spools are nice because they don't have knicks in them like the old ones did BUT the new ones do have a raised area where the mold line was and your thread can get caught on it and cause a tight drag when you sew and wreck havoc. It won't generally throw a machine out of whack but it will affect your stitching. I check for these raised areas before I use the spool and smooth them out with a nail file. If you're using a spool that has a knick in it, make sure, when you put your spool on the machine, that the knick is on the bottom if you are using a top spool pin, or that the thread is mounted on a side spool with the knick facing away from the direction you are threading the machine.
Hope this helps.