How to remove the magnet from the tweeter horn in the PR15 Speakers so I can get to the 3 screws

Yes, but you need to replace the entire speaker. The 1505 and 1508 use a different magnet though they look similar..

There are a number of versions of SP-3, but normally you would remove the screws holding the horn into the cabinet, take out the horn and then unscrew the driver from the horn. At that point, either replace the diaphragm on the driver or the whole driver.

black and red will goto 1 speaker. and blue/yellow to the other. typically red and yellow are + and black and blue are -. the crossover board might tell you which is which where they solder to it. but i'm pretty sure the black/red goto woofer. try hooking up both to woofer and listen to it. 1 way is going to sound horribly wrong lol. that will mean you hooked up the tweeter leads to the woofer. but DO NOT HOOK UP WOOFER LEADS TO TWEETER. thats why i say to do it on woofer.

After removing the back cover disconnect the tweeter cable form the terminal. Then hold the tweeter magnet and turn it anti clock wise. The driver unit will unscrew and come of the horn assembly.
Keep the driver unit on a firm table and unscrew the four + screws. It has a sandwich assembly which will part into two if you put a sharp knife and twist. You will see the tweeter diaphragm which can be lifted up again by using a sharp knife. The replacement diaphragm is available from the below given address
http://reconekits.com/tapcothumpth-15ahorndiaphragmpn0013252-1.aspx

those are Red Dot Lamps. people most comonly know them as red dot fuses, ( whatever ) it just goes on the crossover to protect your hfd. if it blew you might want to take time to check your Tweeter.

The crossover in these is very simple and if it is burned, likely your speakers, maybe both, the woofer and tweeter have been damaged and need to be replaced. Test the speakers before changing the crossover. You MAY NOT notice the damage until you start driving the speakers again. The voice coil of the woofer is a common thing to fry, and while it may not open up, often it becomes unbonded to the coil form and rubs the magnet pole pieces. The tweeter/horn often wipes out the diaphram or blows the element open. Some of these are piezo horns and they can sometimes survive. These are rated at 100 Watts and if your amp can deliver over 50 watts you have to be careful to not put too much power into these. I have several of the Kustom 10 inch ones and several of the 15 inch ones... Also I have two 15 double stacks and they all seem to use the same crossover. Believe me, the crossover is far from what I would call "special" like the advertisements say. As an electrical engineer I was very disappointed. Anyway, test your speakers as they may be the worst of the problem.

i) I believe you can access the fuse by removing the Input Jack Panel.

ii) If fuse is OK, then unscrew the horn unit, take off one speaker wire & measure resistance. If it is open circuit then you can order a replacement horn diaphragm (if you feel confident to fit it to the horn).

Yes it unscrews. Use a oil filter wrench it will make things easier

Here is a site that has PR15 fuses... shown as a 2.1 amp. Very strange value, and it must strictly be for the tweeter portion as 2.1 amps is nothing for a speaker... I don't know that I believe this site.

If you have a Guitar Center near you, inquire there.

Check for impedance ( resistance) in ohms on the speakers disconnected from the circuit using a volt/ohm meter. I think the woofers are 8 ohms and the tweeters are 8 ohms. Also check for bad solder joints where the jacks are soldered to the circuit boards.