Drilling in a hole this small is pretty tough to do,we've found if you pull the needle out it will take the pressure off the screw & it usually turns out using the point of a needle.
You have the foot pressure as tight as it will go loosen it until it starts skipping since it isn't holding the foot down then tighten a turn until it stops.You can run it real loose if you can hold the leather down as the needle is lifting our of the leather to get less marking.
@Seamyher89 Take the bobbincase out & unjam the hook. Then take the cover off under the arm,I think you jammed it & stripped the plastic gear that drives the hook.
Machines like this aren't made to sew finished goods on,they are more for repair where the scratches don't matter.There have been people use some shrink tubing you heat up & put on the foot but then you might have to help feed the leather as it sews because it might slip.
I have a 5 gallon of used motor oil & diesel fuel mixed 50-50 & drop old rusty stuff in it for a few weeks,it comes out pretty stinky but it kills all the rust & soaks in all the bearings,screws & makes it alot easier to tear down.
The biggest difference is the handwheel,it's smaller on the 211 so it'll harder to slow down & some of the parts & screws have been discontinued on it,everything is still available for the 111W.
The leather point for this machine is 16x2 ,.which we have in stock.You'll be able to sew thinner wallets or checkbook covers on this machine & a teflon foot will help he leather slide through easier.
No,get a used Singer 111w,Consew 225,226,Juki 562 or 563 & you'll be alot happier & do a better job of sewing than this one can.This was made to sew clothes using thin thread.
We stock this nut,you could borrow the one off the bobbin winder to try the machine & if you need anymore more parts,needles or thread order it all @ once.
The Singer 211 has a smaller handwheel making it harder to slow down than the other 2 & do to the design of it you can't install a larger pulley on it,for this reason & the fact that a few of the screws for it aren't available anymore would steer me towards one of the others.They both have larger bobbins too.The 167 should have a rubber belt in it,if it's cloth don't buy it.