In light of the recent increase of questions and requests for help to repair broken spyders, here's a collection of the most common questions/problems that spyders have, and the common solutions.
If you're new to the forum, you're encouraged to read this before posting your problem, because chances are you'll find your problem and its solution described within this post.
Spyders are wonderful, reliable markers made out of high grade materials and have decent quality. Granted they're not the best markers out there in terms of technology and the bling factor, but they make great markers for occasional players and the new player that wants to learn with a cheap, good quality marker. And don't talk trash, my 1996 compact, after replacing its broken asa, is still shooting like a dream.
So, down to business.
First, it is important to point out how spyders work. Spyders work with very simple physics. There's 2 sides on the marker, there's the trigger side and the barrel side, you can almost split the marker in half by this. Oh, and there's 2 stages, the upper tube (where the bolt resides) and the lower tube (where the valve resides). Hence the name stacked tube markers. It's worth pointing out that on one side of the valve there is constant gas pressure, and on the other there will be pressure only as long as the hammer is pressing the valve pin.
To illustrate how they work, see this wonderful
gif animation, courtesy of zdspb.com.
On the trigger end of the marker, the sear holds the striker (aka hammer) until the trigger is pulled and the sear is lowered, which releases the striker. The striker is then pushed forward with great force by a spring (the striker, or main spring as it is also called), and the striker with that momentum given by the expansion of the spring, hits the "valve pin", which pushes the valve open and lets gas flow in 2 ways.
One way is the way that about 70% of the gas goes out the upper hole of the valve body to the upper tube of the marker, thus forcing gas into the bolt and the bolt directs that has towards the paintball, which is then shot out. The remaining 30% is used to propel the striker back into the sear, and leaves the marker "recocked".
The back end is composed of, from back to front:
1- On the lower tube you'll have the back plug with the velocity adjustment screw, which is held in place by screws (older spyders) or "quick strip pins" in newer models. The velocity adjustment screw is contained inside the back plug.
3- Still in the lower tube, then you have the striker spring guide (backed by a flat metal disc in older models). The spring guide looks like a nail but it's most commonly made out of plastic or aluminium and it's all rounded.
4- Again, lower tube, you'll have the main spring or striker spring which is the long straight spring that pushes the hammer into the valve.
5- Around that spring you'll have a thick rubber ring, called the striker bumper or hammer buffer, which prevents the hammer from hitting the back of the marker hard when it's propelled back by the gas after shooting.
6- Still on the lower tube. Then you have the all important piece, the hammer. Big elongated heavy steel thing that has the main spring inserted at the back, and has a flat face with just a nipple ad the front.
7- Now the top tube is just the bolt. The bold inserts into the top of the striker and travels with it back and forth as you shoot. Bolts can be made of alumnium (older spyders, need lubrication) or out of delrin (a which plastic polimer that doesn't require lubrication, in fact, lubricating it will damage it).
Then there's the other side of the marker. On the barrel side of the marker there's another set of pieces that work in conjunction with the striker to make the marker shoot. First there's the ASA, whose role is to let gas in. In a basic spyder, the gas will make pressure and move freely up until the valve, which is normally closed. The valve has 7 parts.
1- The valve body, which is the circular piece with 2 holes, one straight through the middle, and another one across from top to bottom. You can tell which is the front and back of the valve by looking at the size of the holes down the middle of it, large hole goes looking at the front (barrel end) and the small holes should be looking to the back (trigger end).
2- The valve has 2 rubber o-rings (often 1 clear and another one black, clear o-ring goes in the front, black on the back), which prevent any leakage of gas around the valve.
3- Then there's the cupseal, which normally is a plastic knob, is in charge of making a tight seal.
3.1- On the other side of the cupseal,
in older spyders, there's a spring guide which looks very much like a ninja star :

. In newer spyders the cupseal is shaped to act as a spring guide as well as a seal on the valve.
4- Attached to the cupseal on the side is the valve pin, which is just a rod with a flattened indentation at one end, and this goes goes into the valve body and will stick out a little bit out the small-hole end of the valve body.
5- And finally, after the valve spring guide (ninja star :

), there's a conical spring, called the valve spring. The role of this spring is to push the valve closed after shooting.
See these videos to educate yourself on how to take apart and rebuild your spyder:
YouTube - Basic Teardown
YouTube - Kingman Spyder valve body rmv
YouTube - Kingman Spyder valve body asmb
And this is the playlist for all spyder videos available from youtube user invictus0:
YouTube - Broadcast Yourself.