Spirits have always been a bit of a problem in SR, either too overpowered or too underpowered. Here are some ideas to help you out with spirits:

1) As said, stick 'n shock ammo is electricity (which is elemental) and bypasses their armor resistance. Additionally, a GM could rule that tracer rounds (which burn to produce a trail) and EX Explosive (which explode) are fire damage, and would also work against them. Also, the high pressure water cannon works, as do flamethrowers and explosives. That means the flamethower, impromptu flamethower (Hair spay +lighter), and HE grenades all work. A prepared runner would probably pack some of this in his pack, because the only thing it wouldn't work on is a fire spirit.

Also, some spirits cannot exist in certain environments. A fire spirit cannot exist in water, so trigger the sprinkler system.

2)Banishing is easy! If you are summoning a force 6 spirit for one combat, chances are it will only have one or two services. Enemy shaman only need one or two hits to get rid of him! Then your spirit summoner has taken all the drain and gotten nothing.

3)A glitch or a critical glitch on a summoning test can be bad news for you. A glitch on a summoning test can result in a spirit refusing to do certain kind of services (like combat) or it can reduce the number of powers it knows. A critical glitch means that the spirit would turn on the summoner (happened to me once.)

Hmm, by the rules no spirit appears if you critically glitch, as you got no successes. You just have something extra bad happen in addition to taking drain.

Degausser, you're thinking of Binding. A critical glitch on that test results in the spirit tearing free, and it might decide to attack the mage.