When I was first shown the Permobil M-300 by the salesperson, I raised my concerns about the very flimsy side arms. The side to side play seemed quite excessive and I was concerned about using them for transferring. The salesperson assured me that they would stand up to repeated transfers but promised to swap these arms out for a new model "which would be available in about three months time". In fact I remember the phrase he used "they would be rock-solid!". In recent conversations with a shop technician, I was told that the Permobil M-300 has only two arm styles, both were available at the time of my purchase and the alternative is less stable that the one I currently have. I was lied to in order to have me commit to the sale!!
Shown here is the Permobil M-300 forward arm post which should drop into the hole shown by the red arrow. While this photo shows about 3/4 of an inch separation between the center of the post and the center of the locking mechanism (hole), the side to side play is even greater. In fact the post and arm can completely miss the mechanisms and the arm would spin around 360 degrees if not stopped by the floor as shown below.
Below is my solution to this poorly designed and engineered sidearm hinge.
I removed all the plastic segments of the broken arm tensioning spacer and replaced them with large metal washers (2 inch outside diameter with 13/16th hole). I reused the central hub which was previously enclosed by the plastic arm tensioning spacer. The bolt (3&1/2 inch in length, 5/16th diameter, #18 Posi-lok nut) (nylon thread resists loosening). All parts obtained from the local hardware store (Home Depot). Tightening the nut seen on the outside of the unit, passing through the hub (not seen) and washers added whatever tension I wanted and would hold the arm in whatever position I wanted. If I find it too stiff, I plan to get one of those thin cutting sheets available in any 'Dollar Store' or kitchen supply store. I find they are made of a thin, somewhat slippery, plastic which is cuttable. Use the metal washer for a template and cut plastic washer to insert between the metal ones to produce a smoother action. I have found this to be unnecessary at the present time.
If I wish, in the future I can get a block of aluminum from a metal supply company and machine my own fancier version, but for now, this works and performance is all I wanted. The arm has very little side to side play. It is stiff side to side but moves smoothly when raised up and down. There is enough tension that the are will stay raised wherever I might place it. It will not slam down either front or back.
Sadly, this is what passes for service these days....
I will have much more to say about this in upcoming posts.