There appears to be similarities with control freezing or control difficulties due to de-icing fluids experienced several years ago.
The de-icing fluid manufactures have implemented changes to the fluid composition, but there is still some residual risk of ‘evaporative dry-out’ and ‘rehydration’ during flight, resulting freezing/blocked control systems. Many manufactures require inspection and/or wash-off action to remove accumulations of ‘gel’ from previous fluid application.
De Ice Fluid residue (Gel) in a control system bearing – not B737.
