As a Smith & Wesson armorer I can speak from A LOT of experience with this weapon system. First, good choice. The 5906 is, IMHO, the best auto pistol Smith ever made. Rock solid, accurate, reliable and very servicable.
The primary problem I have seen with this, and most other firearms, is dirt. Crud builds up in the deep dark crevasses and must be cleaned out for proper functioning. A good, deep cleaning fixes most problems.
For the cleaning to happen you must first take it apart. I have seen people drop field stripped guns in an ultrasonic cleaner and expect that to clean the gun properly. There is no way that is going to happen. It must be taken apart first.
The 5906 has a fairly easily disassembled magazine release.
1. insure weapon is unloaded and remove slide assembly, set it aside.
2. release hammer to take tension off the hammer spring.
3. push out the grip pin (bottom rear of grip frame)
4. put the pin in the hole at the bottom of the grip and pry gently back on the grip. It will slide about halfway off.
5. spread the front of the grips GENTLY with your fingers to allow the grip to come off completely. Make note of the orientation of the hammer spring and the stainless steel cup it sits in.
6. Look at the bagazine release button. It is threaded on and has a spring loaded plunger that keeps it from backing out. You will need a small punch (maybe a large paperclip?) to press in the pin.
7. Depress the pin while unscrewing the mag release button. Small screwdriver or fingernail should work. Unscrew all the way but be careful you do not let the plunger fly away (should not be very difficult)
8. With the plunger removed the mag release will slide out the right side of the frame.
9. Clean the mag release and frame (I use a Q-tip), re-oil and re-assemble.
10. Reasseble in reverse order. The base of the mag release button must be tightened so it is just below the level of the frame (about 1/2 to 1 full turn)
Before you reinistall the grips you might consider flushing out the action with gunscrubber (you do not want to get into the inner workings of the frame w/o some professional training).
There are reduced power springs available from Wolf gun springs (gunsprings.com) but I have found them to be unnecessary as a good clean mag release works very well.