Evening all. Petite lady DIYer making first post. Triton Enrich shower installed about 8 years ago. PRD blew so replaced with new. Tried 2 different types - the original PRD type with the black ball and the newer type with the disc. Both continued to blow. Did the recommended slow turning from 10 (low pressure) to 1 (high pressure) at cold setting to flush, several times without shower head attached. Some debris came out but could hear air being sucked into valve. Re-fitted PRD numerous times and tried all procedures with and without shower head with both types of valve. Ended up in desperation putting PTFE tape carefully around seal where PRD fits into housing. Didn't blow and water pressure steady with and without shower head BUT temperature is alternating scald and freeze. Guessing it's still a PRD issue. Any advice please?