Generally agree with brf.
There is no uniquely best way to set the horizontal tracking angle (HTA) for a pivoted arm. This is different than azimuth and even SRA where in each case there is a best position (even if it varies by disk for SRA). Experts disagree quite a bit on what HTA rule is best. Each possible setting is a compromise. Moreover, for this reason IMO the effect of a different HTA is exaggerated by some people and I am always amused to read that someone spent hundreds and hundreds of dollars on a protractor and came up with an HTA setting that "blew me away." My own suggestion is not to obsess over this setting.
Any of the usual tools used with care will get you to a reasonable solution. The only advice I have is that an even inexpensive tool with a mirrored base can help avoid parallax error.
There is no uniquely best way to set the horizontal tracking angle (HTA) for a pivoted arm. This is different than azimuth and even SRA where in each case there is a best position (even if it varies by disk for SRA). Experts disagree quite a bit on what HTA rule is best. Each possible setting is a compromise. Moreover, for this reason IMO the effect of a different HTA is exaggerated by some people and I am always amused to read that someone spent hundreds and hundreds of dollars on a protractor and came up with an HTA setting that "blew me away." My own suggestion is not to obsess over this setting.
Any of the usual tools used with care will get you to a reasonable solution. The only advice I have is that an even inexpensive tool with a mirrored base can help avoid parallax error.