Before you check the timer, I recommend that you verify that you have the 240 volts supplied to the dryer that is needed for the heater to work. The dryer will run if only one of the 120 volt legs of 240 volt power is supplied to the dryer. If the second leg of 120 volts is missing, your dryer will not heat. Check the house breakers or fuses for the dryer outlet. If they are okay, I recommend that you check the voltage at the outlet. The diagram in the first image below shows one type of 240 volt 4-prong outlet. You can use this diagram as a guide to verify that you have 240 volts at your dryer outlet. NOTE: You should only check this live outlet voltage if you are completely confident in your technical ability to safely measure it using a volt/ohm meter.
If the outlet is okay,
unplug the dryer
and verify the wiring on the terminal block on the back of the dryer. Here is a link for the installation guide for your dryer in case you need it to verify the connections on the terminal block:
If the outlet voltage is okay and the terminal block wiring is good, then you can
unplug the dryer
and access the timer in the console as shown in the second image below. Set the timer in a timed heated cycle. Pull the red wire off and check for continuity between the black wire terminal and the red wire terminal on the timer. You should measure near zero ohms of resistance (continuity). If the contact BK - RD is open (measures infinite resistance or Ol - open load) then the timer is bad and will need to be replaced.
If the timer is okay, then your failure is likely in the wiring or the motor centrifugal switch since all of the other components are okay according to your details.
There is not an easy way to attach the heater element housing to the vent. You may benefit from more working room if you open up the cabinet (with the dryer unplugged) as shown in the third image.
If you need more help, resubmit your question with additional details.