It is not unusual for new users to temperature issues.
There are many factors to consider. First and foremost, are all the cable connections at back of unit firmly connected and secure? Do not use a long high gauge extension cord. If using an extension cord it is best to use a short one with heavy gauge wires.
Plug the unit it in and set temp to max, turn on puck burner and close the upper vent entirely. Let it run for 20 minutes and look inside. The main element should be glowing red for about 75% of its length. A small drop of water on the burner plate should indicate good heat there. Be careful not to get burnt.
These smokers will always be substantially cooler at the top near the vent compared to the back wall mid point where the temp sensor is located. The small element unfortunately struggles to raise temp uniformly within the chamber. By the time the air rises to the top it will substantially cool. This is why it is best to rotate the racks from top to bottom during the cook. frequency of rotation depends on length of cook...long cooks = more rotating.
Vent position also effects heat generation. Generally run wide open for first few hours to allow moisture to escape. Moisture within the smoker will act as a heat sink and pull the temperature down. Having said that, I always set my temp, run the burner with no pucks triggered and allow the smoker 1/2 hour to preheat with the Vent FULLY CLOSED.
Once preheated, I insert my preloaded racks, open vent full and begin cook for an hour or so before triggering pucks. This is with both the heat on and puck burner turned on. After that I will begin the pucks burning and adjust the vent to 3/4 open. Then I run for 2 -3 hours and close the vent to 1/2 open. Idea is to let the moisture initially escape and then gradually choke the vent down as cook progresses. Sometimes I close the vent almost entirely to ensure a thick blanket of smoke towards the end of smoke phase. Once the pucks are finished I leave the burner running to help maintain temp.
It takes time for the smoker to get hot, evaporate moisture coming off the meat and then enable the heat to penetrate the meat. Although slow, this is beneficial because a low and slow cook gives best results. I might cook for as much as 8-9 hours for two metal racks loaded for ribs with smoker set at 220.
Temperature cycles up and down , overshooting the setting by as much as 20 degrees and then dropping below by 10 or 15 degrees. This is just the nature of the operation. Lower racks run hotter than top. I try to run the middle two mostly.
Outdoor temp and wind will affect operation. Choose a location shielded form wind but NEVER near any structure. There is always the potential for fire when you mix heat and animal fat. I never leave the smoker unattended for more than an hour and am always near by. Do not ever allow meat to touch side or back walls.
Keep the water full and check periodically. Open door as infrequently as you can. I adjust racks and service bowl at the same time. It doesn't hurt to put hot water in the bowl to start... just one less item the element has to provide energy to heat.
Once you start to find some success you can explore other options to improve the operation. Some users provide a insulating blanket similar to those used on hot water tanks for cool weather operation or use enclosures for the smoker. Again, you must be aware and take precautions not to create a fire hazard.
Many long time users have either put a larger wattage element in or added a second 500 watt element. I added the second 500 watt element and have never looked back. Heating is no longer an issue for me at all.
You can also add a temp controller that will maintain an accurate and non fluctuating temp.
The more product you place in the smoker the harder it is for temp to be achieved and maintained.
Hope this information doesn't disappoint you however its how it is. With a few adjustments and a little practice with your technique you can be up and running well, happy and eating well. Judging your description of rubbery ribs after 4.5 hours you may well have a problem. I would try the above suggestions provided before getting too concerned. Using the smoker takes a little practise and refinement of technique.
I probably missed a few points. HS will be along to contribute as well.
Have fun.
