After < 3 years our Hybridcare dryer has failed.  The dryer will not spin.  We had someone come and take it apart and the entire inside of the dryer is caked in a thick layer of lint.  We are good about cleaning out both the regular and hybridcare filters so this is a little bit of a concern - seems like a legit fire hazard.  I am told the control board has failed and is $350  to replace plus labor (not counting labor already spent diagnosing, etc.).  We ended up buying a new regular whirlpool duet dryer for $900 installed with a 5 year warranty.  Probably should have gotten a warranty on the  Hybridcare originally.  At least we won't have to wait 2 hours for clothes to dry and deal with the noise anymore.

That's a shame. We have had ours for almost 4 years.
Based on your post, I took the back off and cleaned it out. There was a ton of lint in it. The problem was a foam gasket where the air pipe goes from the heat pump back to the drum. The foam isn't thick enough, and in our case it was displaced as well. Should do a better job and last longer.

We have a LG Washer/Dryer Combo.

Not a heat pump model but close. It uses a couple gallons of cold water to do the condensing for drying. I think it is genius.

It is 120 VAC and doesn't need to be vented. We put our cloths when we go to bed and they are done by morning.

https://www.lg.com/us/washer-dryer-combos/lg-WM3997HWA-washer-dryer-combo

I looked and looked at the heat pump models and then found this one. No holes in the house was a big one for me.