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Recently comma LAMOST-J0240 was identified as a likely second propeller in a cataclysmic variable (CV) system with optical properties that are very similar to the original propellerdoublePoint AE Aqr. Only after the Cycle 29 proposal deadline was the white dwarf (WD) rotation in LAMOST-J0240 detected with a period of just 25s comma making it the fastest spinning WD in a CV binary. We propose ultraviolet spectroscopy of this newly confirmed propeller to tests two theories of magnetic CV evolution. First comma we will use the CIV and NV emission line ratio comma observable only in the FUV comma to test the thermal time-scale mass transfer model as the way to spin-up WDs. Peculiar CNO abundance ratios are a signature of unstable mass transfer that can reach down to the companion star.s core. Inverted NV-CIV ratios are seen in CV systems with WD spin periods between 30s and 40s. Second comma we will test the crystallization theory for generating magnetic fields in WDs by precisely measuring the WD surface temperature. In an analogy with convective planetary magnetic field generation comma only fast-spinning WDs that have cooled to the point of core crystallization form significant fields. Being a propeller comma LAMOST-J0240 clearly has a fast rotating comma magnetic WD comma and the model predicts that its surface temperature should be half of the ground-based limit of 25000K. Further comma the data will establish a baseline for estimating the spin-down age of the WD to constrain the time since the unstable mass transfer event.