Vario problems can be caused by water in the TE probe or leaks in the flask or flask tubing.
Water causes weird vario readings that relate to the pitch of the glider.
The water droplet moves along the tubing when the glider pitches up or down. Dry the lines by disconnecting all instruments and use a fish tank pump to circulate dry air through the tubes. This can take several hours. A leak in the flask can cause the vario to read high at high speeds. Submerge the flask underwater.