I have noticed some concerns regarding decreased effectiveness over time as well as other questions regarding troubleshooting.
So, I will offer some of my own observations.
I was thinking about how the manufacturer came up with the temperature correlation chart and while I do not know with certainty that this is the method he used, what I am about to describe is a foolproof way of determining if the unit is putting out heat.
I removed the ring that holds the silicone O ring, then the metal tube followed by the aluminum grooved ring that holds the screen.
This exposes the resistive heating element.
I have an inexpensive infrared, laser thermometer which I purchased from Home Despot. Unfortunately, the small one I am using is no longer available but you can find relatively accurate ones available either there or on Amazon. I am not talking about noncontact units for measuring human temps but the industrial ones used for scientific purposes....and say for HVAC.
All one has to do is set the thermometer for continuous measurement, turn the unit on, hold it upright while pointing the thermometer's sensor to the heating coil, and trigger the thermometer and then the TM. You will note the increasing temperature. The TM will give you the haptic signal and you will note that the temperature will start to settle.
You can repeat this at several dial numbers if you like. This method can also be used to see what happens after temperature recalibration,
The reason for removing the screen is that one has to remember that the unit is purely convective. The coil is heating the air as it is drawn over the coil. It would be very difficult to use the IR thermometer to measure the air flow.
I am simply demonstrating a method of determining with certainty that the unit is working.
For instance, when the dial of my unit is set....I think it was 6, I am getting about 330 degrees F. (I recalibrated my unit to Red.)
Of course, in terms of operation, the air is going to cool after passing the coil but as everyone knowns, whether you use the stem that comes with the unit, a WPA, or the 3D stem.....all of them get pretty hot which in and of itself tells us that the heating coil is working.
So, it might be a good idea to do this testing when you first get the unit and write the figures down.
I cannot think of any reasons offhand that the unit would decrease in effectiveness over time.....and why tightening the bolt would change anything. The coil is being operated through the circuitry on the board which is either going to work or not work. When you put your battery in you get a clear indication that contact has been made.
I picked up one of the curved metal screens from Amazon that has been used as a modification. My unit had been damaged because I was using the TM dosing capsule with the 3D adapter. To do so, one must use the rimmed basket screen. The capsule protrudes and I must have pushed it too hard damaging the screen. I then took the unit apart and could not get the coil back.
I would NOT recommend using the dosing capsule with the 3D stem.....If you do, please be very, very careful. (I like the TM dosing capsule and I think it works well except with the 3D stem.
As for the screen mod. If you use the screen and do not put the aluminum ring (without or without the mesh screen) the steel sleeve will be loose. I don't think this actually would affect function. It is just perhaps not esthetically desirable :-)
If one just uses the curved screen I notice it has actual holes. I don't think medium ground herb will pass through but I am not sure.
If one removes the mesh screen and uses it over the steel screen.....it is a perfect arrangement for use with the TM dosing capsule.
I actually have been putting the curved screen in first followed by the aluminum ring WITH the screen for both loose herb and the dosing capsule. The setup does work but I had to increase the temperature.
I am curious how many others use the curved steel screen. I am not sure it makes a lot of difference other than it serves well in protecting the heating element.
