Rusted Check Spring
𝗬𝗲𝘁 𝗮𝗻𝗼𝘁𝗵𝗲𝗿 𝗿𝗲𝗮𝘀𝗼𝗻 𝘁𝗼 𝗽𝗲𝗿𝗶𝗼𝗱𝗶𝗰𝗮𝗹𝗹𝘆 𝗰𝗵𝗲𝗰𝗸 𝗮𝗻𝗱 𝗿𝗲𝗽𝗹𝗮𝗰𝗲 𝘁𝗵𝗲 𝘁𝗮𝗸𝗲-𝘂𝗽 𝘀𝗽𝗿𝗶𝗻𝗴: 𝗥𝘂𝘀𝘁!
I was called to service an Infinity recently - about 2 years old with ~10M stitches on it. In addition to routine lubrication and maintenance checks, the customer noted the take-up spring was not returning to the upright position the way it is supposed to and she had intermittent stitch quality issues. Looking at the spring before it was removed there was nothing notably wrong from the outside - like a badly worn area where the thread moves through the hook of the spring - but it definitely did not "spring back" normally - the spring response was very weak. After removing the spring - egads - the entire interior of the spring was badly rusted, so much so that there was a solid covering of rust powder on the bottom of the cavity where the spring is installed in the longarm.
The spring cavity was vacuumed out, and a new spring was installed, and stitch quality was back to normal.
The mystery is how the spring became rusted - the machine was extremely clean and well-cared for, in one of the nicer studios I have visited, and had never been serviced prior to my visit - perhaps the package it was shipped in from the spring manufacturer opened in shipment allowing exposure to air (perhaps even salt-air if shipped from overseas) or did not get a good protective coating in the manufacturing process.
The bottom line - keep an eye on the performance of the take-up spring if you are having stitch quality issues not related to tension or other normal factors - and you should consider replacing the spring every time your machine is serviced along with keeping a spare or two around - at $5 you get a cheap insurance policy.
Quilt on!
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