The good thing is that it is a mechanical issue and should be straightforward to fix. You don't need to be a "techie". If you can use basic hand tools, this is a great beginner problem to solve and see how the mechanisms work.
Look at how the right flipper mechanism is behaving and compare it to the left. You don't need the power ON to move the flipper bats by hand and watch what happens. Also, if you are going to start adjusting/replacing things like coil stops and coil sleeves, DO NOT take apart the left and right flipper at the same time so you can have a good one as a working reference point.
And has been stated repeatedly, no WD40 or any lubrication should be used on any of the moving flipper mechanism parts.
Forest Hill, MD
