Church AV has a very specific set of demands that are very different from those of any other type of venue. The combination of budget restraints, "esthetic" demands and spaces being used for vastly different service styles back to back create a set of very unique problems that most AV technicians are ill equipped to deal with. Many church AV techs are volunteers that do not have the time to thoroughly research all of the products available, and may not have a full understanding of what the industry has to offer.
I offer a variety of consulting services from simply looking at your system and making some suggestions on how to maximize what you have, to making suggestions on what would be an appropriate "next step" to bring an old system up to speed with what your church is doing as well as training sessions with your technicians on how to properly use and maintain the gear you have, because a well trained operator makes all the difference in the world.
I have been directly involved in church AV ministries from all sides (mixing on Sundays, recording services, editing Video, and play instruments) since 2001, and have been working as a professional AV systems designer full time since 2005. In that time I have designed systems for dozens of churches of varying sizes, and have been called in to look at dozens more.
There are certain issues that I see fairly regularly that often get addressed inappropriately
Churches that have perfectly fine gear (sometimes old but still good) and want to scrap it because they don't know how to use or maintain it properly.
This usually manifests as "bad channels on the board," "lots of feedback all of the time," "people can't hear 'x'," or any of a million other "everything used to work fine but now everything is all wacky" sort of ailments. I am not saying that channels don't go bad on a board, or that certain systems can be more prone to feedback, but in about 50% of the cases the equipment was fine or easily reparable, and a more thorough training of volunteers would solve the problem.
I used to mix for a small contemporary worship team that used a portable sound system. The leader didn't fully understand how to do a sound check, and would simply plug into an input on the snake and if he didn't immediately get sound he would declare it a "bad channel," without checking to see if the channel was muted, turned down, or even plugged in yet. Every week I spent fifteen minutes at the end of each service peeling of "bad :(" labels from half of the channels on the snake. There were bad channels on that snake, that probably could have been fixed with 10 minutes of soldering, but the worship leader kept pushing to try to get a new snake because he "never knew which channels would work" and needed something "more stable".
Often in these cases the solution that was being proposed by the churches AV team would not have solved the problem, or would have been very temporary. As an example, I have seen multiple churches have a piece of "pro" level gear that was designed to last for 10 years of concert tour level abuse die after 5 years because no one maintained it. The replacement the church is looking at is usually a low cost "pro-sumer" grade piece that would void the warranty if it was sent on tour. There is a time and place for those products for sure, but if you are looking at replacing a broken snake or mixer, find out when it was last cleaned.
Churches trying to do more than their gear is designed to do.
This is common for churches just trying to start a contemporary service. Using a system that was designed for a speaker, a piano and two choir mics to mix a full rock band will almost always end in disaster. There are a dozen or so ways to properly modify a system to make it work better for a full band, and about a hundred wrong ways that will at best not solve the problem, and at worst damage the existing gear and maybe start a fire (I have seen a 3 year old amplifier in a church spit sparks because the speakers were wired wrong).
Churches spending way too much on gear that will soon be obsolete, replaced in the next upgrade, won't do what they want it to do or won't fix the problem.
This is usually seen in the solution to one of the above issues. Here are some examples.
I used to run sound in a church that was trying to start a video ministry. They decided to run directly out of the FireWire outputs of the cameras and spent hundreds of dollars on active FireWire repeaters to make the signal go the 150' back to the booth. Six months later they got a analog to digital Video converter and switched to using the analog outputs on the cameras, and had a bunch of FireWire repeaters collecting dust. Another church had a poorly maintained 48channel console that died (see the first issue) and tried to replace it with two 24 channel digital consoles chained together because the 24 channel boards were $2500 a piece, and a 48ch console was closer to $10k. After three months they still couldn't get the sync between the small consoles consistently stable and ended up having to but the large console anyway.
The church with the amp spitting sparks? They had called me in to get a quote on a new amp, when in fact the amp was a symptom of a horribly wired speaker network, that would have kept blowing amps up every year until it finally burned the building down.
All of this to say, before you spend a money on new gear to fix a problem, get a professional to look at it (not the guy in the congregation that "knows audio" because he has a big home theater system. That's who wired the speakers that set the amp on fire).