Dewalt 12v Cordless Drill. Same speed in position 1 or 2 ???

http://powertoolshelp.com/dewalt-dc742ka-cordless-hammer-drill-users-manual

The charger for the dewalt 18V battery.
http://www.ezbuybatteries.com/dewalt-72v-18v-battery-charger-universal-replacement-13821.html

Easiest and safest: take the tool and batteries to nearest shop where they sell Dewalt. Ask the guy to let you use their batteries in your tool and vice versa, your batteries in their tool. DYI procedure:To check batteries: - if you have some multimeter, try to measure voltage and if possible also amps (but only for a fraction of the second, if battery is good, amperes shoudl jump up very quickly) - if you have no multimeter, try to find 12V bulb (check spare bulbs for your car), use wire to connect and it should light up. To check tool: open it up, take some 12V DC source, put wires on contacts inside the handle where battery connects. Pull the trigger and it should work. you can try to put wires directly to contacts on the motor. Follow cables from the switch to motor.
Juraj

Is it Nano li-ion? have you got another spare battery to double- check?
I experienced the same problem with 18V Dewalt nano li-ion battery. Was fully charged, came to work- Dead!!! I was lucky I had spare one, so then i was ok, but anyways had to buy a new one. Check on these things:
1. Battery is faulty. If u have any chances to ask someone who has the same gun (voltage is very important!!! has to be the same!!!- 12V battery to 12V gun, 14.4 to 14.4, 18 to 18 etc). Put your battery into that other gun. If You find the same problem that means your battery is dead.
2.Gun with battery contacts. If you 100% sure, that batterIES (check 2 batteries, or more) are OK, check bottom contacts where u put battery in, use WD40, or similar to clean them.
3. Least common Dewalt thing (Most common in Panasonic drills) is trigger contacts.
Basically i do not know what model is your dewalt, i was only talking in general, but there are no miracles- stopped working suddenly, and what u describe new, for instance my new drill dw727kd is less than 1 year old, i was too stuppid to open that battery myself to void warranty :(
AAAAHHH!!!!!! One more thing - If you have not tried to open these screws- check your nearest Dewalt authorised repair center- new NANO batteries have 2year warranty!

Sounds like your brushes are either damaged or the armature is failing the current. Remove the brushes first and inspect them, that is where your arcing is coming from. If the brushes appear ok, your problem is in the armature itself. Regardless of low use, if you store the unit with the battery attached, there are issues with the current draw while stored.

have to replace whole trigger assembly.

worn brushes in the motor can also cause intermittent function, if you havent already checked those. i'd replace those first if they have never been replaced or look worn, broken, cracked, or if springs seem worn.

Hello,
Here is a link for a parts diagram for your model. It has the proper part number that you will need.
Hope this helps.

http://www.toolpartsdirect.com/cgi-bin/schematic.cgi/dewalt/DC988KA_TYPE_1

I would use any 12VDC adapter that has no more than 200mA output. Keep an eye on it. It should be nearly charged within 10 hours. But watch to make sure that niether the battery or the adapter gets too hot. The adapter will get warm, but should never be too warm to touch.

Does the drill do anything? Check in the cavity where the battery goes and make sure there is nothing there to prevent the battery contacts from connecting with switch. I take it the charger indicates the batterys are fully charged. If you cant see anything obvious I would take it back and get a replacement.
Dave

You will need he correct charger, the 24V will destry a very expensive battery.