This tub was installed in my home when it was built in 2002. This is my second time using the tub and the neck/back jets are not working. I have been in contact with the Kohler second tier support team and they emailed me the Service Manual for System II and III Whirlpool tubs which includes the tub I have (K-1348). It looks like this unit is somewhat complicated to work on but I want to try to troubleshoot the issue myself with the help from people on this forum. In the service manual, it talks about a Kohler Whirlpool Test Kit (Part No. 95076) that can be used to troubleshoot all issues with this tub. It looks like the test kit is discontinued. If you have worked on Kohler System III Whirlpool tubs with neck and back jets, please provide me some tips on how to troubleshoot this issue. Additionally, if someone has the Whirlpool Test Kit (Part No. 95076) that I can rent or purchase, please let me know. If you need me to upload the Service Manual, I can try to do that as well.