This weekend I offered to get an elderly lady's knitting machine going; it had been in her attic for about 20 years.
The whole task was a bit of a challenge; the first thing I did was to remove the needle retaining bar (sponge bar) and that was when the trouble started. Most of the needles skewed and appeared jammed. At this point I would say that I've stripped down my Brother knitting machines several times and am very familiar with the process.
It seems that the end of each needle, not the hook end, needs to sit above a spring loaded comb-shaped plate before it slots into a grid at the back of the needle bed. Each needle needed gentle coaxing and manouevering to release it from its jammed position.
Then all needles were soaked in a jar of surgical spirit for a deep clean. The sponge on needle retainer bar had disintegrated and was completely flat. I then cleaned the whole bed with a vacuum cleaner, it was so full of dust and fluff. My vacuum also retrieved a metal double-pointed knitting needle from inside the needle retainer bar tunnel!
The needles were replaced and I ran over the back rail, the heels of the needles and the front rim with lightly oiled cloth. It is now gleaming clean and ready to go.
Things to remember about changing the needle retaining bar is ...
Use a blunt implement to gently push the bar out.
When removing needles, the latches need to be closed.
When inserting needles, the latches need to be open.
Replace any bent, or damaged needles and check that latches open and close easily.
The needle retainer bar goes in metal side up and sits on top of the needles.
The needles need to be held down during the insertion of the needle retainer bar - best done by holding down a few at a time, inserting the bar a little at a time.