These days you can pop down to x-mart and pick up a new Singer HD machine for just under $300.00 and for a time, this machine will likely do what you paid for, and sew pretty much anything you put under the foot. It has a sold medal chassis that is surrounded by a plastic shell and plastic parts and from experience in servicing these Chinese made machines, they really aren’t made for the long haul.
They use a similar drop in bobbin system like the earlier Brazilian made machines which are also known for having issues because the assembly isn’t metal and often breaks. The hook gear and bobbin winder assembly are also plastic and we have seen countless failures in these, and similar machines. replacement parts are available and they can be a little spendy.
Rewind the clock back the the 1960’s and you will find machines like this 1963 Singer 500A that originally sold for around 400.00 in Canada (4000.00 in 2023) that were built to an exceptional standard, with no plastic in the critical drive parts, with a precision made steel bobbin case, and a completely (metal) gear driven drive.
The 500A is a wee bit more fragile than the 401A that preceded it, namely in the top cover and nose plate that can be damaged if you mishandle them but with proper care (it is a precision tool) there should not be any issues.
An old Singer guy once told me that these machines were so much better than many of the new commercial machines and we have customers who use these machines day in and day out to do commercial work with no issues.
The Singer 500A and Singer 401A… just a few examples of mid century machines that will still sew circles around most modern machines. It is rare that any come to us needing anything more than cleaning and lubrication.
There are many more variants of the Singer 4xx series like the 403 and 404 and then there are the German versions of the 4 series that are truly exceptional like the 411G (flat bed) and 431G (free arm), just to name a few.