DW 998 18V.  Practical experience.

Driving screws, working fine, THEN:.

Pulled the trigger, NOTHING

So, figured just getting corrosion on terminal, pulled battery and slammed home, still no action

Dissassembled : The ‘fast-on’* lead to the battery had overheated and melted the nylon insulator, shorting the batt. 

OK, cleaned and soldered the ‘fast-on’ terminal, 5 min epoxy where the nylon melted.

Reassembled, all OK.  BTW, since it was apart, soldered all the ‘fast-on’ clip connections – slightly more power even getting rid of the contact resistance of the stupid ‘fast-ons’.  

* If you are not familiar with the ‘term ‘fast-on’, it is the spade terminal that has a clip go over it.  Whenver I repair anythign with those, first thing is they get soldered.  Just last year I ran into a 3 megwatt Cat DG set that shutdown due to an overheated ‘fast-on’ in the control circuitry and a 100kW uninteruptible computer power system that shut down due to a loose ‘fast-on’.    Cheap for mfg flow times, but poor technical choice for any type connection. 

EDIT BTW:  got the DW a couple years ago at a garage sale, worked OK, guy said he was selling it ’cause it ‘cutout’ occasionally.  Worked OK for me (only occasional use every week or so, nothing professional) for over a year till last week when the problem occured again.