Zanussi TC7102W not heating fully

hello, I am t my wits end trying to diagnose a problem with my tumble dryer. It originally stopped heating at all. At first I replaced the thermostat in the drum. That did not fix it. I then replaced the heater element and it appeared to fix things. However, I quickly noticed that it was as if stuck on the low heat setting. I went through the machine, with a multimeter trying to work out what was going on. All tests led me to believe it was the heater element at fault and the two part element ( the low heat element) was not working. The time logic is correct, there is 240v at the element when they are supposed to be on and the thermostats are all functioning correc readings are as tly ( all normally closed and a clear continuity check from timer through all thermostats). I bought another heater and the problem was not fixed. I have 240V to the heater, only half is getting hot. I have run tests on both heaters, all resistance readings are as manufacturers specs on both and the thermostats are all good. The neutral circuit from the heater is good, it has to be as it it common to both. Both low and normal heat circuits are going live from the timer correctly and I have good continuity from the timer to the element on both wires. Voltage is being applied correctly, just the second stage heater is not getting warm. Any thoughts appreciated.