I have found another Merrylock manual on line for the 2020 and it's in a pdf which is handy for printing. I thought it might help for learning the 3 thread rolled hem....Not sure though as I haven't had a chance to read it yet.
Here is the address for the Merrylock 2020 4 thread overlocker manual (it takes a while to load ). Save the pdf to the desktop for future reference. It may be of some use.
Additional Information on the Merrylock 2020 can be found here Also other Merrylock machines are to be found at SewReview.com too. At present they don't have anything on the Merrylock 740DSA on there. Actually if you are in the market to purchase any new sewing machine or overlocker/serger this is a great site to check out the brands and models, reviews etc.
Merrylock 740DSA manual can be bought here. It's in Euro's and I haven't tried to buy it because I am not sure if it is any different to the one I own that has no rolled hem instructions. If anyone has bought one and it actually has page 29 in it let me know...