[Elecraft] K2 SN 25xx has very low sensitivity in 20 and 80m bands

[Chris]

Hello,

My K2 developed a very weird issue.  The sensitivity is very low in 20 and
80m bands.  It receives but the S-meter reading is much low compared to
other receivers that I compared.  For example, an S9 signal on another good
receiver is barely S1 on K2.  Other bands are fine.

Any advice on where to check first?  Thank you.

DE KM1B Chris