You can repair your septic system problems 99% of the time without digging up your tank or drain field which can cost in the tens of thousands of dollar range.
If you have had actual damage to your system. Have it inspected by a professional who will scope (put small camera down" the system to find the internal breakage. Remember that 99% of the time systems are not "broken" and only need to be cleared of compacted sludge and grime that has accumulated over the years.
If your problem is not mechanical, you need bacteria added. Bacteria acts like acid and will eat through the blockages that have developed. Whatever you do, don't add chemicals!. Chemicals do nothing more that free up sludge and force it further into your system - making things worse.
Find the strongest most aggressive bacteria dealer you can on yahoo, goggle or msn and order a bit more than the recommended dosage. There are many companies selling different products for different situations so make sure you find something strong and get it into your system quickly to get the product working.
Allow the bacteria to do its job. This may take anywhere from a few days to a few weeks depending on how much sludge you have in your tank, lines and field. If you system is very old and has been neglected. The bacteria can take up to 3 weeks but keep in mind, once the bacteria is in the system, it multiplies rapidly and eats everything organic in its path. Bacteria is completely safe and will not harm your system as chemical agents can and often do.
Read about how bacteria works and don't let the repairman tell you that "we" have enough coli-form in our own feces to breakdown our own waste. Not True! Back in the early days when we didn't use bleach, antibacterial soaps and harsh cleaners, we did actually produce enough bacteria in our own stool to degrade and digest our waste but in modern times, it simply does not hold true. Do your research and find out for yourself.
Don’t flush anything down your system that is not bio-degradable.
Try not to use too much anti-bacterial products like hand soap etc. If you do use these products, make sure you add a maintenance dose of bacteria monthly. It will only cost a few dollars and will offset any bacteria killed off by anti-bacterial that you use.
Don’t put chemicals in your system. Paint, bleach and heavy duty cleaners kill most bacteria instantly and your system can't degrade the waste like it should. If you do use these items and they wind up in your tank, use a maintenance treatment.
Don’t drive on your drain field and keep heavy equipment off of it. The weight could break the internal piping and cause a blockage.
Don’t plant trees near your drain field. Keep deep rooted flora away from the system and away from the underground pipe paths (if you know where they are)
Maintain your system with a strong monthly bacteria to prevent unwanted accumulation of sewage and grease.
Never enter your septic system or breath in the fumes. People die all the time when they stick their head down the septic cover to see what is wrong. Septic tank fumes are toxic and deadly!
Never smoke near the septic tank cover or where heavy fumes are present. You could blow up the entire system including your house, yourself and others around you.
Never let the inspector talk you into a new system until you see with your own eyes that the system is damaged. Everything is underground and many repairmen will try to convince you to get a new system. The markup on septic tank installations is incredible. Most systems cost contractors around 2k and they often charge upwards of 25k for a full rework. Get a 2nd and 3rd opinion before doing anything and make sure it is broke and not just clogged. You can have your system scoped with a small camera and you can watch the screen as the scoping takes place. Septic tank scampers are as bad as Jiffy Lube shops so be warned!