I have a Bosch Exccel condenser dryer WLT6305GB/01 FD 8309 200147 it seems to get warm not hot, isn't drying properly, stupidly replaced the heating element and thermostat unit before checking if it could be anything else and that doesn't seem to have helped. The drum still has resistance, and it seems to turn (sounds normal) so I don't think it's the belt. Any assistance gratefully received!

SOURCE: Condenser Dryer turns but no heat

Check with multi-meter for power on the heating element's tags (115/220V). If it does get power,you should replace the heating element. In case of no power- you should replace the thermostat. Good luck!

SOURCE: Dryer Heats - Drum Turns - Clothes Don't Dry - Dryer Seems To Over Heat

Before ripping into the dryer, with the dryer running, check the vent outside. There should be a rather strong air flow. I'll bet you have little or maybe no air flow. Check behind the dryer to make sure you don't have squished flex duct. If you have flex pipe, try running the dryer for a few minutes with the dryer pulled out into the room to stretch the vent out, and check outside airflow again. Try to eliminate all or as much of the flex stuff as you can, replacing it with aluminum dryer vent pipe. (tape joints with foil duct tape) Clean out remaining dryer vent. (there are special brushes you can buy to clean out vents, but they really only work on ridgid pipe.)

SOURCE: dryer not heating hoover 5030d

Some dryers have a thermo-fuse. It doesn't look like a normal fuse. It can look lide another thermost or a long plastic device with two wires foing to it. Also they have a high limit thermost that can open. There is a switch on the motor that won't let power go to the heater until the motor reaches a certain RPM. If this is a 220 volt dryer, it could also be the house circuit breaker. If one half of the breaker is bad or tripped, the motor can still run but you will have no heat. If the dryer has a heat selector switch IE delicate, no heat, or high heat. You should check that for continuity when in one of the heat selection positions. The timer can also cause no heat. Check the timer contacts when it set in a dry cycle. Hope this helps.

SOURCE: Bosch Dryer doesn't dry clothes

With the dryer not connect to the external venting turn the dryer on and see if there is air coming out ot the vent from the dryer. Is this flow of air strong or weak?
If weak then there could be a problem inside the dryer some where. Perhaps the fan is not operating properly. Just my thoughts.

You say you have check the beginning and end of the duck vent pipe. How about seeing if it venting duct is clear from one end to the other.

Good luck

SOURCE: My Bosch Axxis electric dryer Mod. # WTA3510UC

i would check the actual electrical connections, to both the unit, and the downline connections to that actual element itself, its unusual for an elemnt to only go a lilttle bit... it works or it doesn't...
since you seemed to be very knowlegable, ohm
out the element as well as your plug and outlet
ther emay be a loose connection somewhere