Have you talked with the nurse about the low drain to get him/her to help with troubleshooting? Some common reasons for low drain besides the height of the machine relative to the bed are that the catheter has moved from near the rectum where it should be so it can remove as much fluid as possible and/or being constipated as full intestines can adversely affect how well PD fluid drains. Here are some other threads in this Forum related to PD drain issues that might give you some other ideas.
From 2023-2024: PD cyclers-Low drain volume alarm - #6 by system
From 2023: Frequent low drain alerts from Baxter Machine
From 2022: Low drain problem
From 2018: Low Drain Alarm on patient that is disabled
From 2006: PD cyclers-Low drain volume alarm - #6 by system