Unfortunately, due to
a failed cost savings attempt on Pentax' side the solenoid manufacturer Shinmei moving its production from Japan to China, a different (cheaper?) aperture solenoid was used on their K30, K50 and later a slightly? improved version on the K70 model cameras.
There are basically 2 versions of the now famous culprit solenoid used in the Pentax K series: the most recent has a plastic (PET) body of green color and it is made in China. The former/older solenoid used in their older cameras such as the K10, K20, K100 uses a higher quality white teflon (PTFE) body solenoid that was made in Japan.