In 2018 Kenwood stopped including DTMF decode capabilities in the TM-V71A and TM-D710GA radios. I believe the same happened in the E variants as well. I've read that the reason for this is the DTMF chip is no longer available from their supplier. Manuals in these newer radios have notes about wireless operation being unavailable in serials B8610081 and up for the V71A and B8610001 and up for the 710GA. In practice this means the radio can still operate in cross-band repeat mode but you can not send DTMF codes from your HT to change frequencies or functions. This pretty much neuters cross-band repeating. I dug around in the most recent service manuals I can find (TM-V71A and TM-D710 -not G, but similar?. I see where the DTMF chip should be. It's referred to as IC921 and the part number is LC73881M-E. I'm crazy enough that I'm thinking about ordering one, taking apart my radio, and soldering the DTMF chip in. I have two concerns, though. Firstly, I am unable to find exactly a LC73881M-E chip. I have found LC73881M, LC73881M-TL, LC73881M-TLM, and LC73881M-TLM-E. I have not deduced the differences in those parts yet. Looking at the data sheet for the base LC73881M the pin assignments look identical to the service manual diagram. Secondly, the menu options for configuring remote functionality are missing from the models without the DTMF chip. I'm concerned it will not be as simple as soldering in the chip and poof, there are the menus. I know the firmware versions work on all radios, so it's not exclusive firmware locking it out. Attached are some images showing the board and chip in the service manual. I also have found images of boards without the chip as well as variations with the chip. I note that there are some capacitor layout changes on the D/6 board but they appear to have similar values. I posted this on Reddit and some feedback there suggested contacting a Kenwood engineer might be helpful. I plan to call and ask around to see if they can offer any insight. Any additional thoughts on this project would be appreciated!