After turning on the AKTA FPLC, I noticed that the UPC-900 read out the following error message after the self-calibration failed: “73 WARNING Too much straylight leaks in”. The OD ranges from 1000-6000 mAU with double distilled water. My adviser and I replaced the UV lamp and tested both 254 and 280 nm filter housings along with the light housings. The flow cell tubings are non-transparent and the optical unit is not exposed to direct light (the FPLC is kept in a 4°C cold cabinet with no light source). The FPLC is an older model and is no longer serviceable. Are there any suggestions on how to fix the straylight issue?