Do a Cup Up side down.... Bottom UP... Could be 1. a Heater Element problem in the press or 2. a Pressure problem due to wear...

Another trick I had forgot about until now... On some mugs that were cold in my shop and I did not want to turn on my 16 x 20 to heat the bottom... I inserted the bottom 1 inch in the mug press for 30 seconds to a min to warm the bottom WITH the transfer attached.

AL